Global Positioning System (GPS) front-end
receiver circuit
1FEATURES
• Complete single-chip programmable
double-superheterodyne C/A-code GPS receiver
• Programmable high IF frequencies supporting
wideband/P-code GPS and Global Navigation Satellite
System (GLONASS) applications
• Supports frequency plans with a 2nd IF of
4 × f0(1.023 MHz) = 4.092 MHz
• 48-pin LQFP package
•−40 to +85 °C operating temperature range
• 2.7 V minimum supply voltage
• Low DC power consumption [57 mA typical with both
Low-Noise Amplifiers (LNAs) active]
• Power-down mode (<900 µA)
• Typical receiver noise figure at 1.57542 GHz: 4.5 dB
• Typical phase noise −72 dBc/Hz at 10 kHz offset
• Simple microstrip LNA1/2 and first mixer matching
• Single pin VCO with external varactor and resonator
• Digital Phase Locked Loop (DPLL) synthesizer with
programmable VCO, 2nd Local Oscillator (LO) and
reference dividers
• 3-bit synthesizer and power-down control input
• Reference and independent sample clock input with
internal squaring
• 1-bit amplitude quantized and time sampled TTL/CMOS
compatible output driver
• High active gain supporting SAW filter applications
• Configurable for external first LNA applications.
UAA1570HL
2GENERAL DESCRIPTION
The UAA1570HL is a complete single-chip
double-superheterodyne receiver front-end intended for
GPS and GLONASS navigation systems. The IC includes
a programmable on-chip DPLL synthesizer, VCO with
external varactor and resonator, a 1-bit amplitude
quantizer and a time sampled TTL/CMOS compatible
SIGN output bit driver. It can be used with either an active
or passive antenna system by disabling or enabling the
on-chip LNAs and is ideally suited for low power GPS
receiver applications because of its 3 V supply and the
power management features through control pins.
Programmable prescaler controls provide the flexibility of
using different frequency schemes.
The UAA1570HL is optimized to provide SIGN bit data to
the companion Philips part, the SAA1575HL baseband
digital signal processor. The SAA1575HL can provide the
sample clock input to the UAA1570HL by dividing a
TTL/CMOS level reference clock signal down to a
programmable sampling clock output frequency. Both ICs
can also be used independently.
The UAA1570HL is supplied in a low profile, 48-pin LQFP
package for excellent Radio Frequency (RF) performance
and small size.
analog supply voltage2.735V
digital supply voltage2.735V
analog supply current plus digital
VDDD
supply current
G
G
G
G
∆V
RF
IF1
IF2
v(lim)
lim(M)
available RF power gainLNAs at 1.57542 GHz−31−dB
available 1st mixer power gainMX1 at 1.57542 GHz−17.7−dB
available 2nd mixer power gainMX2 at 41.8 MHz−21.4−dB
limiter voltage gain to 1st latchlimiter at 3.48 MHz−78−dBV
differential limiter sensitivity
Global Positioning System (GPS) front-end
receiver circuit
5BLOCK DIAGRAM
handbook, full pagewidth
CCA(LNA1)
LNA1GND1
V
P42GND
V
CCA(LNA2)
LNA2GND1
LNA2IN
BIASGND2
LNA2GND2
LNA2OUT
CLOCK
1
2
3
LNA2
4
5
6
7
to data register
LNA1GND2
BIASGND1
LNA1OUT
48 47 46 45 44 43
LNA1IN
LNA1
UAA1570HL
DIVIDE-BY-1 or 2
P41GND
DIVIDE-BY-1 or 2
COMP
4042 4139 38
PHASE
FREQUENCY
DETECTOR
DIVIDE-BY-2
DIVIDE-BY-N
(64 to 127)
UAA1570HL
P39GND
PLLGND
(1)
DATA REGISTER
PROGRAMMING
SCLK
37
SQUARING
CIRCUIT
FOR
36
V
CCA(PLL)
35
DGND
33
V
DDD
31
V
CCA(LIM)
32
DATA
8
9
10
11
12
SQUARING
CIRCUIT
VCO
13 14 15 16 17 18
MXPGND
REFIN
V
CCA(VCO)
TANK
VCOGND
P12GND
Shaded blocks are NOT active during synthesizer state.
(1) The default values are: L = 10, N = 71 and R = 4.
MX1IN
DIVIDE-BY-R
(4 to 31)
MX1GND
CCA(MX1P)
V
IF1P
(1)
DIVIDE-BY-2
DIVIDE-BY-L
(4 to 15)
IF1N
to data
register
23
STROBE
DIVIDE-BY-3
(1)
DIVIDE-BY-2
19 20 21 22 24
CCA(MX2)
V
MIXER 2MIXER 1
IF2INN
MX2GND
IF2INP
QUANTIZER
IF2P
34
30
29
28
27
26
25
MHB269
SIGN
BFCP
LIMINP
LIMINN
BFCN
LIMGND
IF2N
Fig.1 Block diagram.
1999 May 105
Page 6
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
6PINNING INFORMATION
PIN VOLTAGE
SYMBOLPIN
V
CCA(LNA2)
12.75LNA2 power supply: DC operation range 2.7 to 5 V; use close
LNA2GND1200LNA2 ground 1: minimize RF ground inductance
LNA2IN30.8150.807LNA2 input: use external RF AC coupling
BIASGND2400LNA2 bias circuit ground: minimize RF ground inductance
LNA2GND2500LNA2 ground 2: minimize RF ground inductance
LNA2OUT61.483.629LNA2 output: use external RF AC coupling. The DC voltage is
CLOCK7CMOS levelCMOS levelSerial interface clock input: this DC coupled CMOS CLOCK
REFIN81.693.99Reference input: use external AC coupling. The DC voltage is
V
CCA(VCO)
92.75VCO power supply: DC operation range 2.7 to 5 V; use critical
TANK101.921.92VCO negative impedance resonator port: use the absolute
VCOGND1100VCO ground: minimize RF ground inductance; use critical
P12GND1200this pin provides additional RF shielding and has to be
MXPGND1300RF mixer preamplifier ground: minimize RF ground inductance
MX1IN140.820.81RF mixer preamplifier input: use external AC coupling and RF
MX1GND1500RF mixer ground: minimize RF ground inductance; use critical
V
CCA(MX1P)
162.75RF preamplifier/mixer power supply: DC operation range
IF1P172.75RF mixer IF positive output: DC couple this output pin to the
TYPICAL VALUES (V)
VCC= 2.7 VVCC=5V
DESCRIPTION
proximity RF decoupling to pins 2, 4 and 5
approximately 1.3 V below the V
CCA(LNA2)
supply on pin 1.
input moves 20-bit programming words into the synthesizer
DATA input register while the STROBE is LOW. A DC
short-circuit to ground is recommended with the default
frequency plan.
approximately 1 V below the V
CCA(PLL)
supply on pin 36.
close proximity RF decoupling to pin 11
minimum trace lengths and widths and keep the loop to the VCO
ground pin 11 as short as possible, while centring the COMP
output voltage at pin 40 within the charge pump output voltage
range given in Chapter 1 1 by adjusting the resonator inductance
and/or required AC coupling component.
close proximity RF decoupling to VCO supply pin 9
connected to ground
matching
close proximity RF decoupling to V
CCA(MX1P)
supply pin 16
2.7 to 5 V; use critical close proximity RF decoupling to pin 15
V
CCA(MX1P)
supply through first IF filter inductors or RF chokes.
Capacitively decouple the supply near the output inductors.
Balanced first mixer IF1 outputs are recommended. Prevent
externally squared reference harmonics from entering the first IF
signal path or components.
1999 May 106
Page 7
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
PIN VOLTAGE
SYMBOLPIN
IF1N182.75RF mixer IF negative output: DC couple this output pin to the
V
CCA(MX2)
192.75IF mixer power supply: if present, decouple the common V
MX2GND2000IF mixer ground: minimize IF ground inductance; use close
IF2INN210.9830.98IF mixer negative input: use external AC coupling. Balanced
IF2INP220.9830.98IF mixer positive input: use external AC coupling. Balanced
STROBE23CMOS levelCMOS levelSerial interface strobe input: a LOW level on this DC-coupled
IF2P242.75IF mixer second IF positive output: DC couple this output pin
IF2N252.75IF mixer second IF negative output: DC couple this output pin
LIMINN281.6963.999Negative limiter input: AC couple this pin to the second IF filter
TYPICAL VALUES (V)
V
= 2.7 VVCC=5V
CC
DESCRIPTION
V
CCA(MX1P)
supply through first IF filter inductors or RF chokes.
Capacitively decouple the supply near the output inductors.
Balanced first mixer IF1 outputs are recommended. Prevent
externally squared reference harmonics from entering the first IF
signal path or components.
CC
line sourcing the first and second mixer by placing a large
decoupling capacitor between the two
proximity IF decoupling to the V
CCA(MX2)
supply pin 19
IF1 second mixer inputs are recommended. Prevent externally
squared reference harmonics from entering the first IF signal
path or components.
IF1 second mixer inputs are recommended. Prevent externally
squared reference harmonics from entering the first IF signal
path or components.
CMOS STROBE input enables the CLOCK input to load the
20-bit programming word into the synthesizer input DATA
register. A mandatory DC short-circuit to ground is required to
ensure that the default frequency plan is invoked on power-up.
to the V
CCA(MX2)
supply through second IF filter inductors or RF
chokes. Capacitively decouple the supply near the output
inductors. Balanced second mixer IF2 outputs are optional for
many applications. Short the unused IF2P or IF2N output directly
to the supply in single-ended applications.
to the V
CCA(MX2)
supply through second IF filter inductors or RF
chokes. Capacitively decouple the supply near the output
inductors. Balanced second mixer IF2 outputs are optional for
many applications. Short the unused IF2P or IF2N output directly
to the supply in single-ended applications.
AC couple this pin to ground in close proximity to the pin.
The DC voltage is approximately 1 V below the V
CCA(LIM)
supply
on pin 31. No DC coupling.
output or to ground if unused with single-ended filter
applications. The DC voltage is approximately 1 V below the
V
CCA(LIM)
supply on pin 31. No DC coupling.
1999 May 107
Page 8
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
PIN VOLTAGE
SYMBOLPIN
LIMINP291.6963.999Positive limiter input: AC couple this pin to the second IF filter
BFCP301.6963.999Positive limiter input DC feedback loop decoupling:
V
CCA(LIM)
312.75Limiter, sample clock squaring and sampler Emitter
DATA32CMOS levelCMOS levelSerial interface data input: this DC-coupled CMOSDATA input
V
DDD
332.7
SIGN34TTL outputTTL outputAmplitude and time quantized second IF output signal:
DGND3500SIGN bit TTL output driver sink ground: critically isolate this
V
CCA(PLL)
362.75Synthesizer power supply: decouple in close proximity to
SCLK371.342.5Sample clock squaring input: accepts LOW-level AC coupled
PLLGND3800PLL ground: minimize ground inductance; use close proximity
P39GND3900this pin provides additional RF/IF shielding and has to be
TYPICAL VALUES (V)
VCC= 2.7 VVCC=5V
5
(independent
of VCClevel)
(independent
of VCClevel)
DESCRIPTION
output or to ground if unused with single-ended filter
applications. The DC voltage is approximately 1 V below the
V
CCA(LIM)
supply on pin 31. No DC coupling.
AC couple this pin to ground in close proximity to the pin.
The DC voltage is approximately 1 V below the V
CCA(LIM)
supply
on pin 31. No DC coupling.
Coupled Logic (ECL) circuits power supply: decouple in
close proximity to pins 26 and 31. If present, isolate from the
common VCC line sourcing the first and second mixer by placing
a large decoupling capacitor between this block and the mixers.
accepts 20-bit programming words into the synthesizer data
input register, while the STROBE is LOW, on the rising edge of
the CLOCK input. A DC short-circuit to ground is recommended
with the default frequency plan.
SIGN bit TTL output driver power supply: critically isolate and
separately decouple this digital V
analog (V
) supplies. Maintain minimum trace lengths to
CCA
supply from all other
DDD
decoupling components. Particular attention should be applied to
prevent coupling into V
CCA(LIM)
pin 31. If SAA1575HL is used,
use the digital supply from the back-end.
extreme care should be taken to isolate this sampled TTL output
signal from all analog traces and components, particularly the
second IF filter components at the limiter input. Avoid coupling
into the reference oscillator signal trace.
digital supply ground from all other analog supplies and grounds.
Maintain minimum trace lengths to decoupling components.
pin 38
sample clock inputs directly from the PLL reference oscillator or
DC-coupled externally squared digital clocks derived from the
PLL reference oscillator after external frequency division. The
maximum DC-coupled input level at pin 37 should not exceed
75% of the V
CCA(LIM)
half the supply value on V
decoupling to the V
supply value. The threshold level is set at
CCA(LIM)
CCA(PLL)
pin 31.
supply pin 36
connected to ground
1999 May 108
Page 9
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
PIN VOLTAGE
SYMBOLPIN
COMP40depends on
P41GND4100this pin provides additional RF/IF shielding and has to be
P42GND4200this pin provides additional RF/IF shielding and has to be
V
CCA(LNA1)
LNA1GND14400LNA1 ground 1: minimize RF ground inductance
LNA1IN450.8150.807LNA1 input: use external RF AC coupling
BIASGND14600LNA1 bias circuit ground: minimize RF ground inductance
LNA1GND24700LNA1 ground 2: minimize RF ground inductance
LNA1OUT481.483.629LNA1 output: use external RF AC coupling. The DC voltage is
432.75LNA1 power supply: DC operation range 2.7 to 5 V; use close
TYPICAL VALUES (V)
V
= 2.7 VVCC=5V
CC
depends on
VCO
application
VCO
application
DESCRIPTION
Charge pump phase frequency detector output: the PLL loop
filter is connected in shunt and close proximity to this pin. The
PLL loop filter tuning control voltage should be routed to the
external VCO varactor circuit using minimal trace lengths in
complete isolation from all potential coupling sources.
connected to ground
connected to ground
proximity RF decoupling to pins 44, 46 and 47.
approximately 1.3 V below the V
CCA(LNA1)
supply on pin 43.
1999 May 109
Page 10
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
handbook, full pagewidth
LNA1IN
LNA1GND1
V
45
44
43
UAA1570HL
CCA(LNA1)
V
CCA(LNA2)
LNA2GND1
LNA2IN
BIASGND2
LNA2GND2
LNA2OUT
CLOCK
REFIN
V
CCA(VCO)
TANK
VCOGND
P12GND
BIASGND1
LNA1OUT
LNA1GND2
48
47
46
1
2
3
4
5
6
7
8
9
10
11
12
P41GND
P42GND
42
41
COMP
40
PLLGND
P39GND
39
38
SCLK
36
35
34
33
32
31
30
29
28
27
26
25
V
CCA(PLL)
DGND
SIGN
V
DDD
DATA
V
CCA(LIM)
BFCP
LIMINP
LIMINN
BFCN
LIMGND
IF2N
UAA1570HL
13
14
15
16
17
MX1GND
CCA(MX1P)
V
IF1P
MX1IN
MXPGND
Fig.2 Pin configuration.
1999 May 1010
18
IF1N
19
20
MX2GND
CCA(MX2)
V
21
IF2INN
22
IF2INP
2437
23
IF2P
STROBE
MHB270
Page 11
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7FUNCTIONAL DESCRIPTION
The programmability of the UAA1570HL and flexible
interface definitions allow the device to be configured for a
wide range of applications. To restrict the content of this
document the functional description of the device will
generally concentrate on the C/A-code application circuit
based on the default frequency plan.
The application circuit does not allow easy measurement,
calibration and documentation of the many sub-block
characteristics which ensure good system performance.
Therefore, test boards have been developed which allow
direct measurement of the sub-block characteristics.
The tables and graphs reflect the UAA1570HL
specification as derived from simulation and measured
results in these characterization board environments.
The tables and graphs do not directly specify application
board expectations. The functional description however,
focuses on the default application.
The RF system diagram (see Fig.3) illustrates the default
application of the UAA1570HL in the Philips GPS
demonstration board. In this application the UAA1570HL is
intended to be operated directly from a passive GPS
antenna through a very short antenna cable. Any cable
loss in this demonstrator adds directly to the system noise
figure and should therefore be minimized.
UAA1570HL
LNA1 can be powered down in the UAA1570HL to
accommodate applications built around external LNAs,
typically where long antenna cable runs are required.
The first LNA is assumed to be matched with a 2nd-order
band-pass structure to provide some input selectivity,
since no dielectric or SAW filter has been used in the
demonstration board. It should be noted that low loss RF
SAW filters now make it possible to significantly improve
the jam immunity of this amplifier, by placing a SAW filter
at the output of the antenna.
On the demonstration board the first LNA is followed by a
low loss RF SAW filter (<2.4 dB).
On the demonstration board the second LNA has been
matched to 50 Ω using a simple transmission line
structure.
Finally, another identical RF SAW filter follows the second
LNA into the first mixer.
1999 May 1011
Page 12
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
handbook, full pagewidth
L = 1020 mils
W = 8.8 mils
C326
ISOLATE THE REFERENCE INPUT AND
ITS HARMONICS FROM THE FIRST IF
AND ITS FILTERING COMPONENTS
REFIN
C307
V
J301
BPF301
SAW
C306C320
VRF
R314
C339
tune
L = 217 mils
W = 33 mils
50 Ω
line stretcher
analog ground
digital ground
C327C328
L = 900 mils
W = 8.8 mils
L = 286 mils
W = 6 mils
100 Ω
C323
L = 412 mils
W = 6 mils
100 Ω
C331
D301
BPF302
SAW
CLOCK
REFIN
C338
R316
R307
L = 355 mils
W = 6 mils
C334
L305
100 Ω
VRF
C322
VRF
line stretcher
C321
1
2
3
4
5
6
7
8
9
10
11
12
L = 386 mils
W = 6 mils
100 Ω
L = 376 mils
W = 33 mils
50 Ω
C324
L = 315 mils
W = 6 mils
100 Ω
C330
R311
C325
VRF
C335
C313
R322
VRF
C346
V
UAA1570HL
C332
R310
L307L306
tune
C316
C315
R315
C305
C341
C340
C319
R306
L304
L303
C314
R319
STROBE
C317C318
384847464544434241403937
231314151617181920212224
OPTIMUM PERFORMANCE REQUIRES
THAT THE GPS DIGITAL BASEBAND,
SUPPLY REGULATORS, AND OTHER
SOURCES OF DIGITAL NOISE BE PLACED
IN THIS RELATIVE ORIENTATION TO THE
UAA1570HL.
SCLK
36
35
34
33
32
31
C337
30
C311
29
C312
28
C336
27
26
25
DATA
C310
SIGN
R305
UAA1570HL
ISOLATE THESE DIGITAL SIGNALS,
SUPPLIES, AND GROUNDS FROM
ALL ANALOG RF FUNCTIONS.
C329
V
DDD
C347
C303
L302
L301
R301/C301
C301
C309
C304C302
R323
C308
L309
L308
C345
MHB271
Fig.3 UAA1570HL RF system diagram (default application).
1999 May 1012
Page 13
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.1Low noise amplifiers LNA1 and LNA2
Two identical LNAs are provided on the IC although LNA1
need not be biased, if sufficient external gain is provided
by an external LNA. The input stage of each amplifier
consists of an unbalanced common emitter and a cascode
stage. The AC-coupled output stage is a compound
feedback bootstrap amplifier. Each stage is independently
biased and regulated. LNA1 can be disabled by
connecting the respective supply (pin 43) to ground. LNA2
has to be powered-up even if not used.
Each LNA can supply a power matched gain of
approximately 15.5 dB with an associated noise figure of
3.7 dB.
Both LNAs have −1 dB input compression points of
approximately −22 dBm from a 3 V supply. The 2nd and
3rd-order input intercepts are approximately
−7.9 and −13 dBm, respectively, in a power matched
environment.
The RF match impedances at L1 (1.57542 GHz) are
provided in Table 1 for all RF inputs and outputs.
Table 1 RF matching impedances
PIN
REAL PART
(Ω)
4531−j32LNA1 input
4877.5+j6LNA1 output
324−j25LNA2 input
674.5−j0.5LNA2 output
1433.5−j25.51st mixer input
IMAGINARY
PART (Ω)
FUNCTION
UAA1570HL
These RF port impedances are marked on the following
Smith charts (see Figs 4 to 8; normalized to 50 Ω) and
suggested matching structure netlists are provided. They
contain transmission lines defined by their characteristic
impedance Z (in ohms), their electrical length E (in
degrees) and the operating frequency f (in GHz).
Capacitors C are given in pF. TLIN is a series
transmission line and TLOC is an open-circuit stub
transmission line. Node 1 is the UAA1570HL RF port
being matched and Node 0 is ground. These matching
networks are structurally identical to those illustrated on
the GPS application block diagram, however, the
component values in the application diagram are
somewhat different to account for stray capacitances and
other real world influences. The netlists are derived from
EEZMATCH software (Besser Associates, Los Altos, CA,
USA).
Generally, we assume a minimum shunt capacitance, due
to the IC pin pad and adjacent pin strays, of approximately
0.25 pF as an initial stray element in the netlist below, that
will always be present in the matching structure design.
This value should be re-estimated and matched if the
layout introduces significant additional strays at the pin
pads.
1999 May 1013
Page 14
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
7.1.1LNA1IN
CAP10C=0.25 ! C1 C = PF
TLIN12Z=97.0 E = 34.5 F = 1.57542 ! TL1 Z = OH, E = DEG, F = GHZ
CAP 2 0 C = 2.0 ! C3 C = PF
Alternatively the 2 pF shunt capacitance at the input of the 97 Ω matching line above might be replaced with a 25 Ω
microstrip open stub if space permits.
TLOC20Z=25.0 E = 26.1 F = 1.57542
handbook, full pagewidth
0.5
0.2
1
2
5
+ j
0
− j
0.2
0.2
0.5
0.51
2
1
Fig.4 LNA1 input impedance and matching network.
10
5
10
∞
10
5
2
MHB318
1999 May 1014
Page 15
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
7.1.2LNA1OUT
To facilitate matching of both LNA outputs, a small shunt capacitance should be placed as close as possible to the output
pin pad increasing the assumed 0.25 pF lumped pin capacitance by approximately 0.5 pF to 0.75 pF. This ensures that
a simple, short, high impedance transmission line will provide a good 50 Ω match at high gain. A via to the opposite side
of the board right at this output pin allows a stub or chip capacitance to be added without comprising the characteristics
of the 97 Ω matching line.
CAP10C=0.25 ! C22 C = PF
IND128L=0.7!L7=NH
CAP280C=7.1658792e−1 ! C23 C = PF
TLIN 28 29 Z = 97.0 E = 26.239010 F = 1.57542 ! TL15
If an open line stub is used, the latter components have to be replaced by:
TLOC 280Z=20.0 E = 8.0 F = 1.57542 ! OTL7 Z = OH, E = DEG, F = GHZ
TLIN 28 30 Z = 97.0 E = 26.2 F = 1.57542 ! TL16 Z = OH, E = DEG, F = GHZ
handbook, full pagewidth
1
0.5
0.2
+ j
0
− j
0.2
0.2
0.5
0.51
2
1
Fig.5 LNA1 output impedance and matching network.
2
5
10
5
10
∞
10
5
2
MHB319
1999 May 1015
Page 16
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.1.3LNA2IN
CAP10C=0.25 ! C13 C = PF
TLIN 1 14 Z = 97.0 E = 30.0 F = 1.57542 ! TL9 Z = OH, E = DEG, F = GHZ
CAP140C=2.3309277 ! C14 C = PF
handbook, full pagewidth
+ j
− j
0.5
0.2
0
0.2
0.5
1
1
2
UAA1570HL
2
5
10
5
10
∞
10
0.2
0.5
1
2
Fig.6 LNA2 input impedance and matching network.
5
MHB320
1999 May 1016
Page 17
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
7.1.4LNA2OUT
CAP10C=0.25 ! C22 C = PF
IND131L=0.1!L8 L=NH
CAP310C=0.5!C24C=PF
TLIN 31 32 Z = 97.0 E = 25.077020 F = 1.57542 ! TL17 Z = OH, E = DEG, F = GHZ
In the event that the second capacitor is replaced by an open line stub, the last two components have to be changed:
TLOC 310Z=20.0 E = 5.5 F = 1.57542 ! OTL8 Z = OH, E = DEG, F = GHZ
TLIN 31 33 Z = 97.0 E = 24.460094 F = 1.57542 ! TL = 18 Z = OH, E = DEG, F = GHZ
handbook, full pagewidth
0.5
1
2
0.2
+ j
0
− j
0.2
0.2
0.5
0.51
2
1
Fig.7 LNA2 output impedance and matching network.
5
10
5
10
∞
10
5
2
MHB321
1999 May 1017
Page 18
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
7.1.5MX1IN
CAP10C=0.25!C5C=PF
TLIN 1 13 Z = 100.0 E = 31.083933 F = 1.57542 ! TL9 Z = OH, E = DEG, F = GHZ
CAP130C=1.673902 ! C6 C = PF
Again an alternative open stub line is suggested which could be used to replace the 1.67 pF capacitance at this end of
the previous netlist.
TLOC 130Z=25.0 E = 23.0 F = 1.57542 ! OTL5 Z = OH, E = DEG, F = GHZ
handbook, full pagewidth
0.5
0.2
1
2
5
+ j
0
− j
0.2
0.2
0.5
0.5
1
1
2
Fig.8 MX1 input impedance and matching network.
10
5
10
∞
10
5
2
MHB322
1999 May 1018
Page 19
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
7.1.6GENERAL REMARKS AND RESULTS
The RF match has an important effect on the gains, noise figure, and dynamic characteristics of the RF system blocks.
Reflection coefficients better than −15 dB are easily attainable and can be improved to better than −25 dB with attention
to details.
Fig.9 Typical LNA fundamental, 2nd and 3rd-order product output levels as a function of input level.
In the following graph (see Fig.10) the solid trace G
(dB) represents the measured frequency response of the
LNA
UAA1570HL LNAs as measured on a spectrum analyzer, while the dotted and dashed results were obtained using a
noise figure meter over a more restricted frequency range.
30
handbook, halfpage
G
LNA
(dB)
20
10
0
1575.42
(2)
(1)
(3)
MHB273
15.3
3.68
(1) LNA gain (dB).
(2) Power gain.
(3) Noise figure.
−10
0100020003000
f (MHz)
Fig.10 Typical LNA gain and noise figure as a function of frequency (50 Ω power matched on the input and
output).
1999 May 1019
Page 20
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.2Correlation of the UAA1570HL data sheet,
application and test boards
The application circuit does not allow easy measurement,
calibration and documentation of the many sub-block
characteristics which ensure good system performance.
Therefore, test boards have been developed which allow
direct measurement of the sub-block characteristics.
These boards use a 1 : 16 Ω ratio RF transformer to
transform 50 Ω to the more appropriate value of 800 Ω at
IF frequencies. The high-impedance side of these
transformers is terminated with a physical resistor to adjust
the UAA1570HL impedance at the port being measured, to
approximately 800 Ω. This ensures that a calibrated signal
is applied or received in the 50 Ω test environment.
The transformer provides marginal performance at
41.8 MHz, so calibration results for this transformer are
also included in this document.
The 800 Ω impedance environment is somewhat less than
that used in the application board. The UAA1570HL
Characteristic tables provided in this document are
calibrated to this 800 Ω environment as quantified in the
notes at the end of the table. The effects of the transformer
and associated termination losses have also been
removed to some extent, so that specifications reflect the
performance of the IC. The measured graph results were
all derived from the test boards and corrected to again
reflect part performance as much as possible.
However, this was not always possible, so some
discussion concerning the measurement limitations is
provided where appropriate. Where possible, fundamental
design relationships and limitations are indicated.
UAA1570HL
In addition to the direct effects of power losses introduced
by the transformer (approximately −1.3 dB at 41.82 MHz),
which are reflected in the measured S21 results, the test
board results may also be impacted by deficiencies in the
transformer 1 : 4 voltage step-up ratio at 41.8 MHz;
however, this has not been quantified.
An additional correction must be made to the current test
results to compensate for internal 4 pF shunt capacitors on
each collector output of the first mixer, which have not
been resonated out in the testing.
The first mixer measurements also include a 3 dB loss due
to the 800 Ω transformer termination. This loss is also
removed from the specification result. The second mixer
has similar 2.1 dB input and 3 dB output transformer
termination losses removed from the specification.
For measurements made at 3.48 MHz in the second IF,
0.4 dB must be added to the measured results to reflect
transformer losses at IF2, also.
In summary the measured gain of the first mixer has been
increased by 1.3 dB (transformer IL) + 1.4 dB (capacitive
roll-off effects) + 0.2 dB (gain match) + 3 dB (output
transformer termination loss) or 5.9 dB to calibrate out
these losses in the specification.
The measured gain of the second mixer has been
increased by 1.3 dB (input transformer IL) + 1.7 dB
(input term loss) + 0.4 dB (output transformer IL) and
+ 3 dB (output term loss) or 6.4 dB to calibrate out these
losses in the specification.
The following two graphs (Figs 11 and 12) reflect the
measured performance of the 1 : 16 Ω ratio RF
transformer used to test the IF functions. Two transformers
were placed back-to-back to make these measurements.
Figure 11 represents the transmission function of just one
of these transformers over frequency. Figure 12
represents the associated return loss at one input with the
second transformer terminated into 50 Ω. In the actual
UAA1570HL test board a single transformer is terminated
in 800 Ω.
1999 May 1020
Page 21
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
handbook, halfpage
0
S
21
(dB)
−1
−2
−3
−4
−5
0100
20406080
UAA1570HL
MHB274
(2)
(1)
(3)
f (MHz)
(1) S21; T
(2) S21; T
(3) S21; T
amb
amb
amb
= −40 °C.
= +25 °C.
= +85 °C.
Fig.11 S21 for the test measurement transformer.
20
handbook, halfpage
S
11
(dB)
10
0
−10
−20
−30
0100
(1)
(2)
(3)
20406080
MHB275
f (MHz)
(1) S11; T
(2) S11; T
(3) S11; T
amb
amb
amb
= −40 °C.
= +25 °C.
= +85 °C.
Fig.12 S11 for the test measurement transformer.
1999 May 1021
Page 22
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.3RF mixer with preamplifier
The 1st mixer (the RF mixer) consists of an RF
preamplifier followed by a Gilbert cell mixer. The RF
preamplifier consists of the same unbalanced common
emitter and cascode stage as used in the LNAs, but
without the compound feedback bootstrap output stage.
The cascode output is AC-coupled into one side of the
lower tree of the Gilbert cell mixer. The other side is
internally AC-coupled to mixer ground via a 20 pF
decoupling capacitor. The Gilbert mixer RF input is
degenerated with low loss inductive emitter feedback to
increase the effective −1 dB compression point and
intercept points. Referenced to the preamplifier input, the
−1 dB compression point and 3rd-order intercept point are
−25.4 dBm and −16.3 dBm, respectively. Another
important first mixer parameter is its 2nd-order input
intercept point, which will extrapolate to approximately
1.38 V (peak value) differential or +12.8 dBm in the 50 Ω
mixer input environment.
The differential output of the Gilbert cell mixer is
open-collector to allow optimization of conversion gain and
matching to the first IF filter over a wide range of
frequencies and filter options. The total conversion gain is
therefore determined by the real part of the effective output
load, which is given by the IF filter input impedance and
loss and/or fixed filter input matching networks, if present.
The voltage conversion gain can be estimated by
multiplying the effective single-ended to differential
transconductance value for the first mixer (0.0531 A/V) by
the total effective differential output resistance. The total
power conversion gain to a differential load can be
estimated from the voltage conversion gain by subtracting
diff_load
10
----------------------log
50 Ω
the output resistance is distributed between the fixed
output termination, the IF filter input impedance, as well as
equivalent loss impedances associated with the finite Q of
filter components. The assumption has also been made
that the output impedance which the mixer sees is real, at
least in the IF band.
. The total power delivered by the mixer to
UAA1570HL
Therefore, the test circuit voltage conversion gain is
estimated at 0.0531 A/V times the effective differential
loading of approximately 440 Ω. This results in a voltage
conversion gain of approximately 27.4 dBV. Subtracting
9.4 dB to convert from power in a 50 Ω environment to
power into 440 Ω, we see that the first mixer delivers a
total power conversion gain of approximately 18.0 dB in
the test circuit. It is important to note that approximately
3 dB of this available power gain is lost in the test circuit
output transformer termination and that much of this power
can be recovered in application circuits.
The peak differential output voltage swing of the mixer
should be limited to less than approximately
1 V (peak value) or 2 V (p-p) differential or
0.5 V (peak value) single-ended to prevent clipping by the
internal output ESD protection diodes and to prevent mixer
output saturation. This implies that effective differential
output loads of approximately 2.5 kΩ could result in
clipping at the output of the mixer.
The first mixer output structure also supports single-ended
first IF filter applications. By taking one of the mixer outputs
to the supply rail, the other can drive a single-ended first IF
filter, thereby reducing external component cost in some
applications. Maintaining the same single-ended loading
impedance, as in the differential case (i.e. double the
effective single-ended load) results in the same peak
voltage across the same load, even with only half the
transconductance
same power is delivered to the same filter load and the
conversion gain remains the same. However, an effective
load of 1.25 kΩ would also bring this single-ended mixer
output to the same clipping point as the full differential
equivalent load of 2.5 kΩ. The maximum recommended
first mixer single-sided voltage conversion gain (input to
one output) is therefore approximately 32 for both
single-ended and differential output applications.
The power matched Double-Side Band (DSB) noise figure
of the RF mixer with preamplifier is approximately 12 dB at
1.57542 GHz from a 3 V supply.
1
⁄2(0.0531 A/V) available. Therefore the
Note: The open-collector outputs of the first mixer each
include internal 4 pF capacitors to ground. These
capacitors should be included in the design of the first IF
filter by removing 2 pF from the differential input
capacitance for balanced filters and 4 pF from
single-ended designs.
1999 May 1022
Page 23
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
Fig.13 Typical first mixer fundamental, 2nd and 3rd-order product output levels as a function of input level.
MHB277
VCC (V)
(1) F
(2) F
(3) F
DSB
DSB
DSB
; T
; T
; T
amb
amb
amb
= −40 °C.
= +25 °C.
= +85 °C.
20
handbook, halfpage
F
DSB
(dB)
16
12
8
4
0
2345
(3)
(2)
(1)
Fig.14 Typical RF mixer noise figure as a function of temperature and supply voltage (test board).
1999 May 1023
Page 24
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.4VCO
The VCO consists of a single transistor in common
collector configuration with internal positive feedback
realized by capacitors connected from emitter to ground
and emitter to base. Together with the external
resonator/inductor, this is a typical Colpitts circuit. With the
transistor’s base connected to pin 10 (TANK), the internal
circuit arrangement produces a large negative input
impedance at this pin.
At V
initially biased with approximately 1.5 mA of start-up
current. This value is relatively constant varying from
approximately 1.56 mA at T
T
higher due to the large amplitudes involved leading to
rectification and bias point shifting.
The VCO operates as a negative impedance oscillator with
a suitable external inductive resonator.
= 3 V and T
CCA
= −55 °C. During operation, the average currents are
amb
=27°C the oscillator transistor is
amb
= +120 °C to 1.4 mA at
amb
UAA1570HL
Series or parallel resonators can be used, while tuning is
achieved by an external varactor diode.
VCO gain as well as the out-of-loop bandwidth phase
noise are dependent on the choice of external elements
used here. Consequently, they should be selected with
great care; their quality factor is especially important and
should be as high as possible.
Finally, the VCO is followed by a differential buffer stage
with emitter follower inputs splitting the signal to the divider
and LO driver stage path to increase isolation between
mixer and synthesizer and their wanted or unwanted
signals.
This first buffer stage is followed by two other specialized
buffer amplifier stages in the individual signal paths
bringing the signal to the required levels for driving a mixer
or a divider.
100
handbook, full pagewidth
R
(Ω)
0
−100
4
C
(pF)
2
0
(1) T
(2) T
(3) T
= −55 °C.
amb
= +27 °C.
amb
= +120 °C.
amb
(1)
(2)
(3)
2.5
MHB278
(1)
(3)
(2)
f (GHz)
Fig.15 Simulated VCO small signal negative resistance (top diagram) and capacitance (below), without strays.
300.511.52
1999 May 1024
Page 25
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
2.4
handbook, halfpage
2.0
1.6
1.2
0.8
0.4
0.4130.80.62
(1)
(2)
UAA1570HL
MHB279
f (GHz)
(1) Corrected for strays.
(2) Raw data 3 V supply voltage.
Fig.16 Magnitude of the reflection coefficient of VCO negative resistance tank pin (measured).
handbook, halfpage
0
Φ
(deg)
−40
−80
−120
−160
−200
0.4130.80.62
MHB280
(1)
(2)
f (GHz)
(1) Corrected for strays.
(2) Raw data 3 V supply voltage.
Fig.17 Phase of the reflection coefficient of VCO negative resistance tank pin (measured).
1999 May 1025
Page 26
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.5First IF filter
The first IF filter provides four functions:
1. It provides selectivity to protect the 2nd mixer (the IF
mixer) from high level spurious RF signals which pass
through the wide band-pass envelope of the RF filters,
typically 40 to 60 MHz.
2. The filter attenuates thermal noise and spurious
signals in the 2nd mixer image band.
3. It can provide impedance matching/transformation
from the RF mixer output to the IF mixer input.
4. It can reject spurious common mode and/or differential
signals generated by high level local sources such as
harmonics of the reference clock or sample clock.
The first IF can be structured to support a wide range of
single-ended or balanced filters including LC or SAW
realizations. High RF gain provides first IF signal levels
high enough to accommodate first IF filter losses of 15 dB
with optimum RF matching and conversion gain in the first
mixer.
The Philips application board uses a 6th-order coupled
resonator filter based on the butterworth response.
The design method is described in the
FILTER SYNTHESIS”
tables formulate single-ended filter designs which we later
convert to a balanced form.
The initial centre frequency and bandwidth were 41.82 and
4.5 MHz, respectively. The following list illustrates the
tabular design 3 dB down k and q parameters from Zverev
that were developed for the initial single-ended structure.
This tabular listing was chosen based on the desired
selectivity and minimal insertion loss, which could be
realized with available surface mount inductors operating
with quality factors (Q) in the range of 40 to 50.
The impedance level is determined by the choice of design
inductance (165 nH), with foresight given to eventual
balancing of the design. Maximizing the load presented to
the first mixer was also a consideration. With some
frequency plans stability in both the first and second IF will
also need to be considered when choosing the impedance
level of the design.
by Anatol Zverev. The handbook
“Handbook of
UAA1570HL
= 331 Ω
R
s
Tank 1 = 165 nH in parallel with 81.6 pF
Coupling capacitor 1 = 6.2 pF
Tank 2 = 165 nH in parallel with 74.9 pF
Coupling capacitor 2 = 6.7 pF
Tank 3 = 165 nH in parallel with 81.1 pF
RL= 690 Ω.
To convert this filter to a balanced design it can be
mirrored in the ground plane which would result in the
following balanced structure. It should be noted that the
tank design inductances have doubled while the tank
capacitances have halved, which can be seen by
removing the virtual ground plane. The series elements
remain unchanged in the balanced design, while the
differential source and load have of course doubled.
Rs= 663 Ω
Tank 1 = 330 nH in parallel with 40.8 pF
Coupling capacitor 1 = 6.2 pF
Tank 2 = 330 nH in parallel with 37.5 pF
Coupling capacitor 2 = 6.7 pF
Tank 3 = 330 nH in parallel with 40.6 pF
RL= 1380 Ω.
To optimize the power developed by the first mixer its load
was maximized by driving the 1380 Ω side of this filter.
It was also decided to bias the output of the first mixer
through Tank 3 components by breaking the former
differential 330 nH inductor back into two 165 nH inductors
connected to the supply which also acts as a virtual
ground.
The filter was then resimulated in ‘SPICE’ to optimize
against available discrete surface mount component
values with finite quality factors. All filters must be driven
by their design impedances to produce their prescribed
response. Since the finite quality factors of the filter
inductors emulate an equivalent shunting load of
approximately 2 ×π×f×L×Q, the source and load
terminating impedances can be increased to compensate
for this parasitic element while maintaining ideal filter
response and minimizing losses. In the default application,
R322/306 in conjunction with the equivalent parallel
resistance at the respective filter input and output give the
desired terminating impedance.
The handbook calculations result in a preliminary
single-ended three shunt tank structure with a coupling
capacitor between each tank as follows:
1999 May 1026
Page 27
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
The limitation imposed by image noise is illustrated in
Fig.18 where the ideal calculated filter response is
compared against the measured noise density at the
output of the first IF filter. The single sided FET probe
measured result was corrected by +6 dB to account for
balanced processing and
or −11.2 dB to accommodate power conversion losses.
The IF noise density selectivity is seen to be limited by the
available RF gain and noise figure of the first mixer. At the
image frequency, 34.86 MHz, the measured noise floor is
approximately 13 dB below the desired IF level at
41.82 MHz. This will result in an image contribution to the
noise figure of the system of approximately 0.2 dB.
10 log
handbook, halfpage
50 Ω
---------------663 Ω
−120
N
d
(dBm/Hz)
−130
34.86 × 106/sec41.82 × 106/sec
UAA1570HL
The in-band noise density can be estimated based on the
single-ended voltage gain to the output of the IF filter. With
the antenna thermal input level at approximately
−174 dBm/Hz, noise figure of approximately 4 dB and
voltage gain from the antenna to the IF filter output of
approximately 47 dBV (at 5 V supply voltage), we can
expect the differential noise power density to be
approximately −174 dBm + 4 dB + 47 dBV + 6 dB
(conversion to balanced) −
or −129 dBm/Hz. The final term converts the measured
power using a high impedance FET probe, calibrated to a
50 Ω environment, to the actual 663 Ω differential filter
output environment.
Fig.18 First IF filter output noise power density (application board).
−140
−150
−160
(2)
(1)
30
3450
384246
f (MHz)
1999 May 1027
Page 28
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.6Second IF mixer
The second mixer is a standard Gilbert cell mixer operating
with a total tail current of 4.3 mA, which is Proportional To
Absolute Temperature (PTAT). The RF input, or lower tree
of the mixer, is not internally terminated other than by 5 kΩ
biasing resistors to each input. With no significant emitter
degeneration, the real part of the RF port input impedance
is dominated by the two differential junction Rπs in parallel
with the bias elements. The differential output of the Gilbert
cell mixer is open-collector to allow the conversion gain
and matching to the second IF filter to be optimized over a
wide range of frequencies and to many types of IF filters.
The conversion voltage gain is determined by the tuned
real part of the effective output load. This load may consist
of the IF filter input impedance as well as fixed filter input
matching compensation terminations and losses.
The voltage conversion gain can be estimated by
multiplying the effective differential conversion
transconductance value (0.0294 A/V) by thetotal effective
differential load at the output of the mixer.
The conversion power gain is best described relative to
specified mixer input and output impedance environments.
The power conversion gain is calculated by subtracting
of the voltage conversion gain of the mixer. It should be
noted that differential second mixer input terminations may
be DC-coupled.
We can simplify and estimate the second mixer conversion
gain in the default application by noting that the input
impedance environment is approximately 663 Ω, while the
output environment is approximately 1394 Ω. With
effective output loading of 854 Ω (2.2 kΩ in parallel with
0.7 × 2 × 996 Ω) the voltage conversion gain can therefore
be expected to be approximately 25.1 V/V or 28 dBV.
The power correction from 663 Ω at the input to 1394 Ω
(0.7 × 2 × 996 Ω) at the output is −3.2 dB, so the resulting
power conversion gain is approximately 24.8 dB.
The factor of 0.7 in the calculation of the impedance level
is explained in Section 7.7.
It should be noted that a balanced coupled k filter can be
converted to a single-ended equivalent with a
single-ended input impedance exactly equal to that of the
full differential filter by keeping the same tank resonator
components, but placing the series coupling capacitors in
single-ended series (i.e. halving the differential value) and
AC grounding one side of the tanks.
from the dBV value
UAA1570HL
The demonstration board was converted from a balanced
second IF filter in this manner.
To optimize the noise figure of the second mixer the input
termination admittance should be reduced. However, this
will be at the expense of the mixers input compression and
3rd-order intercept characteristics. Since the RF input of
the IF mixer is a simple differential stage, the input −1dB
compression point and 3rd-order intercept points are
relatively fixed at approximately 67 and 215 mV
(peak value), respectively, in the second mixer. This
results from noting that an undegenerated differential input
can be expected to have an input−1 dB compression point
of approximately 36.6 mV (peak value) differential. With a
small additional extrinsic emitter degeneration the −1dB
compression point is raised to approximately
67 mV (peak value) differential. This is approximately
−24.7 dBm in the 663 Ω second mixer GPS application
input environment with the 3rd-order intercept point being
approximately 10 dB higher at −14.6 dBm. Another
important second mixer parameter is its 2nd-order input
intercept point, which will extrapolate to approximately
79.8 V (peak value) differential or 36.8 dBm in the 663 Ω
mixer input environment.
The peak output voltage swing of the IF mixer should be
limited to a peak differential swing of less than
approximately 1 V (peak value) or 2 V (p-p) differential to
prevent clipping by the internal output ESD protection
diodes and to prevent mixer output saturation. This implies
that an effective differential output load of approximately
3.2 kΩ could result in clipping at the output of the mixer.
The IF mixer supports single-ended first and second
IF filter applications. A single-ended input is implemented
by AC bypassing one side of the IF mixer input to ground
and accepting an associated drop in mixer conversion
voltage gain. It should be noted that single-ended input
terminations can still be DC-coupled to the mixer input pins
by using the above mentioned bypass capacitor. The IF
mixer output can be made single-ended by connecting the
unused mixer output to the supply rail.
Extra care should be taken to characterize single-ended
first IF applications. Using a single-ended second IF filter
in combination with a balanced first IF filter may help reject
common mode signals not rejected by the first IF filter.
However, it should be noted that the differential tank
capacitors of the fully differential IF filters can be replaced
by common mode capacitors by doubling the differential
value and connecting two of these capacitors to ground.
Any distribution between these two extremes is also
acceptable.
1999 May 1028
Page 29
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
As with the RF mixer maintaining the same single-ended
load as an effective differential load would result in the
same voltage applied to the equivalent resistance.
However, a single-ended effective load of 1.6 kΩ could
also bring this mixer output to its clipping point.
The maximum recommended second mixer single-sided
voltage conversion gain (one input to one output) is
therefore approximately 16 for both single-ended and
differential output applications.
The estimated Single-Side Band (SSB) noise figure of the
IF mixer is approximately 7.5 dB at T
3 V supply with an input termination matching resistor of
2kΩ. Removing the termination results in an expected
noise figure of 4.9 dB from a 1 kΩ source. This
degradation is distributed between the input termination
input loss and approximately a 1.6 dB increase in the
actual mixer noise figure.
The conversion gain is expected to be relatively supply
independent, increasing by only approximately 0.5 dB
from a supply value of 2.7 to 5.5 V. The IF mixer RF
bandwidth is also expected to only increase by
approximately 4%, while the mixer noise figure is expected
to decrease by less than 0.1 dB as the supply is increased
over the same supply range.
The IF mixer RF bandwidth, if not resonated, is dominated
by the mixer differential input capacitance of
approximately 1 pF.
=27°C from a
amb
UAA1570HL
With tuned inputs, the IF mixer RF input bandwidth can be
extended quite high, but practical consideration warrant
that the RF filter terminating the input should provide band
limiting, thereby restricting the RF high frequency roll-off to
less than 200 MHz without special characterization efforts.
This is also, generally, the upper limit that the
programmable synthesizer supports. The noise figure of
the IF mixer as well as the limiter can be expected to
degrade as the operating frequencies are increased.
For example, at 200 MHz in a terminated 100 Ω system
the DSB noise figure of the IF mixer will increase by at
least 10 dB to approximately 18 dB. If stability permits low
impedance first IF filters can be matched into the IF mixer
using step-up matching circuits such as baluns or
transformer like tuned networks, to minimize the
degradations.
The input compression point and noise figure of the IF
mixer, as measured in the characterization test board, are
plotted against temperature and supply voltage in
Figs 19 and 20. The characterization test board employs
the 1 : 16 Ω ratio transformers to provide a 50 Ω match to
the 800 Ω test environment. The losses of the input and
output transformers, as well as transformer insertion
losses at 41.82 and 3.48 MHz, have been removed before
plotting. Therefore, this graph correlates to specification
and expected performance of the second mixer in the
referenced 800 Ω environment.
−24
handbook, halfpage
CP
−1dB
(dBm)
−26
−28
(1) T
(2) T
(3) T
amb
amb
amb
= −40 °C.
= +25 °C.
= +85 °C.
−30
2345
Fig.19 IF mixer −1 dB input compression point (800 Ω test circuit).
1999 May 1029
MHB282
(3)
(2)
(1)
VCC (V)
Page 30
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
Fig.20 IF mixer DSB noise figure (800 Ω test circuit).
20
handbook, halfpage
output
(dBm)
0
−20
−40
−60
−80
−100
−90−70−50−10
(1)
(2)
MHB284
(3)
−30
input (dBm)
Fig.21 Typical second mixer fundamental, 2nd and 3rd-order product output levels as a function of input level
(800 Ω environment).
1999 May 1030
Page 31
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.7Second IF filter
The second IF filter provides five functions:
1. It provides selectivity to protect the limiter input from
spurious signals which pass through the first IF
band-pass filter envelope, typically 5 MHz wide.
2. The filter attenuates undesired second mixer output
products, such as the LO leak, to levels which will not
block/capture the following limiter stage.
3. The filter defines and shapes the noise bandwidth to
be amplitude quantized.
4. It can provide impedance matching/transformation
from the IF mixer output to the limiter input while
maintaining stability.
5. It can reject spurious common mode and/or differential
signals generated by high level local sources such as
harmonics of the reference clock or sample clock and
digital processing noise from associated devices such
as the SAA1575HL.
The second IF can be structured to support a wide range
of single-ended or balanced filters including LC or ceramic
realizations. The available system gain can provide
second IF signal levels sufficient to accommodate high
second IF filter losses.
The Philips application board again uses a 6th-order
coupled resonator filter based on the butterworth
response. The design method is described in the
“Handbook of FILTER SYNTHESIS”
Initially a skewed centre frequency and bandwidth were
input at 3.1 and 1.75 MHz, respectively, to help overcome
the asymmetry which is intrinsic in geometric low
frequency band-pass filter designs as they approach DC.
The following table design 3 dB down k and q parameters
were used:
This filter was originally mirrored by a virtual ground to
convert it to a balanced form, but later the balanced
components were converted back to a single-ended form
(to reduce component count) simply by placing the
balanced series capacitors in series on one side of the
filter (effectively halving the capacitance value) and
grounding the opposite side of the tanks where these
series capacitors were removed. This effectively maintains
the differential power gain while only using a single-sided
output.
by Anatol Zverev.
UAA1570HL
The filter was then resimulated in ‘PSPICE’ to optimize
against available discrete surface mount component
values. Finally the filters input and output direction were
reversed to ensure that the highest impedance side was
placed at the mixer output to maximize the available power
developed. A 909 Ω termination was used at the output of
the filter to terminate the 4.87 kΩ limiter input. This
effective 766 Ω termination is somewhat lower than the
initial design value of 2 × 548 Ω or 1096 Ω and therefore
develops approximately −1.56 dB less power with respect
to second mixer loading. The reduction of the impedance
level by 30% (or a factor of 0.7) was done in order to have
a large safety margin against instability of the
limiter/quantizer path. Instability can be caused here by
the large small-signal gain associated with this signal path
in conjunction with the high signal levels present at the
SIGN output. Furthermore, due to the strong
non-linearities present in this signal path, LO2 leakage in
conjunction with the IF2 itself can produce signals at the
IF1 frequency and thus enter the IF1 filter together with the
wanted signal. This impedance level reduction is passed
through the second IF filter and consequently lowers the
mixer 2 conversion gain by approximately 30%, too.
The filter design was determined to be sufficiently tolerant
to this adjustment by observing the effect on the filter’s
output noise response with respect to unstable peaking
and maintaining the desired selectivity response. Care
must be taken not to induce instability while observing the
IF2 filter noise response by using a 10 : 1 divider in
conjunction with a very low capacitance RF FET probe
(<0.5 pF).
In the default application, R323/305 in conjunction with the
equivalent parallel resistance at the respective filter input
and output give the desired terminating impedance.
The frequency of the mixed down third harmonic of the
reference oscillator is usually the most significant spurious
product which is generated in the default frequency plan
and must be kept at least 13 dB below the integrated noise
response of the filter. For example, typical true power
noise densities (Dn) for a nominal GPS demonstration
board operating at 3 V are expected to be approximately
−100 dBm/Hz differential at the input of the limiter and
reflect the importance of designing a well matched RF
system. Assuming that a somewhat lower gain variation
has been realized with a noise density of approximately
−105 dBm/Hz over an estimated 2 MHz noise equivalent
bandwidth, it is possible to evaluate and measure the
associated spurious product level that would result in a
−13 dB jammer-to-noise (J/N) and 0.2 dB system noise
figure degradations as follows:
1999 May 1031
Page 32
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
The true power of a product at the output of the second
IF filter in a 1 kΩ environment should be no more than
−105 dBm/Hz + 63 dB − 13 dB or approximately
−55 dBm. The equivalent single-sided measurement with
a 50 Ω calibrated probe would be
55 dBm–10 log
+
or −44.6 dBm. Figure 22 illustrates the true noise power
density as measured points for this lower gain case.
The filter response of the first IF filter is translated to the
second IF and superimposed at the second IF to show that
the 3rd harmonic reference spur at 43.2 MHz, is not filtered
by this response.
−90
handbook, halfpage
(dBm/Hz)
3.48 x 106/sec4.86 x 106/sec
N
d
548
--------- 50
UAA1570HL
Also shown is the second IF filter response and the
combined first and second IF filter selectivities, which
account for total observed selectivity noise response.
For difficult applications which require higher losses in the
IF filters, self jamming can be minimized by choosing a
reference and frequency plan which places the harmonics
of the reference exactly at the second LO frequency,
where they are benign.
MHB285
−110
−130
−150
04816
(1) IF1 filter response superimposed on IF2 filter response.
(2) IF2 filter response (calculated).
(3) IF2 filter noise density (measured).
(4) IF1 filter response translated to IF2 frequency.
Fig.22 Second IF filter output noise density frequency response on the application board.
(1)
(2)
(3)
(4)
12
f (MHz)
1999 May 1032
Page 33
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.8Time and amplitude quantization
After frequency conversion in the double-superheterodyne
portion of the UAA1570HL and filtering to approximately a
2 MHz bandwidth in the second and final IF filter, the
frequency translated thermal noise from the GPS
pass-band around the L1 carrier is ready to be converted
to a digital signal for processing by the companion GPS
chip-set part (SAA1575HL). First the thermal noise’s sign
is determined by amplitude quantization in a 1-bit hard
limiter. This asynchronous information is then time
quantized by latching in a master/slave D-flip-flop to
complete the analog-to-digital conversion process. Finally,
this ECL digital SIGN bit data is translated to TTL levels
and sent to the SAA1575HL.
Four differential stages are used to hard limit the thermal
noise in the final IF. The total gain is approximately
63.9 dBV with a bandwidth of roughly 66 MHz and a noise
figure of approximately 11.3 dB in a 1 kΩ environment.
The parallel equivalent differential input impedance of the
limiter is 4.87 kΩ in parallel with 0.3 pF. Offset control is
provided through 42.5 kΩ feedback resistors from each
balanced output back to the inputs. External decoupling
capacitors cut the feedback loop for AC signals.
Limiter inputs as low as 25 µV (peak value differential) are
resolved at the output master flip-flop DFF1 in its
transparent mode. As the master flip-flop is latched
positive feedback resolves metastable states. While the
master flip-flop is in its transparent state the positive
feedback in the slave flip-flop will resolve the remaining
metastable states as it is latched.
UAA1570HL
The first is LO leakage from the first mixer output which will
couple into the package die pad through internal 4 pF
common mode capacitors at the output of the 1st mixer.
This leakage signal is effectively filtered at the 2nd IF filter
output, but reappears internally on all down-bonded
grounds. It appears at a level of approximately 0.5 mV
(peak value differential) across the limiter input transistor
bases with an assumed 1st mixer input RF offset of
approximately 1 mV.
The second is LO leakage from the second mixer.
Assuming 1.5 mV RF input offset, the leakage at the
output of the second IF filter is expected to be
approximately 500 µV (peak value differential) (−69 dBm
into 1 kΩ) and sets the worst case nominal process
blocking level. With a nominal −50 dBm IF thermal level at
this point there is a 19 dB margin to blocking. To prevent
blocking, IF filter losses should be minimized and the
selectivity of the single-ended or differential second IF filter
has to be designed and characterized to maintain this
leakage product at least 11 dB below the integrated
second IF filter thermal noise signal.
The third form of blocking can occur if LO1 leakage is
sufficiently high (greater than 15 mV (peak value) on the
die pad) to be injected into the 2nd mixer regulators and all
down-bonded IF grounds. This results in burst of LO1
leakage at the 2nd mixer LO2 zero transition points which
increase LO2 leakage peaks by factors of 10.
The gain response of the limiter from a low impedance
source with no input strays is illustrated from the input to
the output of each stage in Fig.23.
Three forms of LO leakage can block the limiter if they
capture the device.
1999 May 1033
Page 34
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
80
handbook, full pagewidth
G
(dB)
0
−80
−160
−2
10
−1
10
11010
(4)
(3)
(2)
(1)
2103
UAA1570HL
MHB286
4
f (MHz)
10
(1) Limiter input.
(2) 1st stage gain response.
(3) 2nd stage gain response.
(4) 3rd stage gain response.
Fig.23 Limiter input, 1st, 2nd and 3rd stage gain response as a function of frequency (simulated).
1999 May 1034
Page 35
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
R
i(diff)
(kΩ)
8
6
4
2
0
−2
10
−1
10
11010
(3)
(2)
(1)
handbook, full pagewidth
2103
UAA1570HL
MHB287
4
f (MHz)
10
(1) T
(2) T
(3) T
= −55 °C.
amb
= +27 °C.
amb
= +120 °C.
amb
Fig.24 Limiter differential input resistance as a function of frequency (simulated).
7.8.1CLOCK INPUTS
Both the reference and the sample clock input can be
driven by a Temperature Compensated Crystal Oscillator
(TCXO). Typical TCXOs produce 0.5 to 1.0 V (p-p) clipped
sine wave outputs. The drive capability is typically 20 kΩ in
parallel with 5 pF or 10 kΩ in parallel with 10 pF. Some
TCXOs are even capable of driving loads as low as 1 kΩ
without buffering.
Alternatively, cost can be reduced by designing a simple
discrete crystal oscillator reference, paying careful
attention to temperature tolerance (±6 ppm) as well as
shock and vibration characteristics.
Both UAA1570HL clock inputs, the synthesizer reference
input REFIN (pin 8), and the sample clock input SCLK
(pin 37), accept low level inputs and provide internal
gain/squaring circuits.
The reference clock input has a high impedance with
20 kΩ in parallel with 0.07 pF. A high stability, low phase
noise crystal reference source should be AC-coupled to
this port. Reference inputs up to 35 MHz and levels
between 50 to 500 mV (peak value) are acceptable. This
source can be externally squared and attenuated before
being applied. Direct sinusoidal inputs should be as large
as possible within the prescribed range to optimize phase
noise performance.
The sample clock input also features a high impedance of
23.3 kΩ. The sample clock input can be AC-coupled
directly to the reference if the system sampling objectives
are met. Alternatively, the TCXO/XO reference can be
externally squared to CMOS input levels and applied to the
SAA1575HL RCLK input (pin 98) and divided under
firmware control to produce a signal commensurate with
the sampling objective.
Due to the wide range of programmable frequency plans
and sampling rates supported by the UAA1570HL, it is not
possible to predict the frequencies and levels of the
associated spurious products that will be generated.
One significant source of potential spurs are the
harmonics of the reference and sampling signals. The
availability of on-chip squaring circuits provide some
freedom to minimize large digital signal effects in sensitive
RF circuit areas. In most cases digital sampling signal
levels are acceptable as long as careful attention is paid to
avoid injecting these signals or their harmonics into the
pass bands of the IF filters.
1999 May 1035
Page 36
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
The SCLK input of the UAA1570HL is self-biased at 50%
of the analog supply voltage (V
threshold level. It is therefore possible to operate this input
with levels as low as 10 mV (peak value) in order to avoid
large digital signal flow on the Printed-Circuit Board (PCB)
runners. This is done in the default application with a
6.8 and 3.9 kΩ resistive divider followed by a 10 pF AC
coupling series capacitor in between the SAA1575HL and
the UAA1570HL.
However, when it is nevertheless intended to use full
CMOS or TTL levels, some attenuation is required so that
the peak sample clock input does not exceed 75% of the
UAA1570HL analog supply voltage. This is especially
important while the UAA1570HL is operating from a lower
supply (3 V) than the SAA1575HL (5 V). A resistive divider
can help in these cases, but the AC coupling method
described above should be preferred.
7.8.2CMOS
TO ECL SAMPLE CLOCK SQUARING CIRCUIT
The UAA1570HL internal sample clock squaring circuit
allows single-ended sinusoidal clock inputs as low as
10 mV (peak value) over a frequency range from
5 to 35 MHz. The rise time of the clock output should be in
the order of 25% of the maximum sampling frequency to
ensure that aperture losses are less than approximately
1 dB (0.91 dB). The period of a 35 MHz clock is 28.57 ns.
To keep the sampling aperture on the order of one fourth
this period implies a rise time of 5.7 ns is
required and should also be kept with lower sampling clock
rates.
Using a 14.4 MHz sampling rate test signal into the SCLK
input results in good TTL eye pattern characteristics over
a measured input range down to at least −25 dBm.
At −35 dBm the effects of slew rate limiting begin to appear
with the eye pattern closing beyond −40 dBm.
7.8.3T
IME QUANTIZATION (SAMPLER)
Two clocked D flip-flops are connected in a master/slave
configuration to implement the sampling function of the
1-bit sampler. With the internal DFF clock (CLK) LOW the
master flip-flop DFF1 is in its transparent mode and
continuously follows the amplitude quantized limiter
output. As the clock (CLK) goes HIGH the data is latched
in the master flip-flop and the slave DFF2 becomes
transparent to the latched output from the master flip-flop.
The falling edge of the CLK signal latches the slave and
again loads the limiter output into the master flip-flop.
These stages also provide additional limiting gain for
marginal input signals from the limiter.
) near the internal
CCA
28.57 ns
---------------------- -
41.25×
UAA1570HL
Since the TTL/CMOS output stage is transparent the SIGN
bit output is updated on the rising edge of the CLK with the
master latched and the slave transparent. This implies the
DSP can expect SIGN bit data to be latched on the LOW
CLK state.
7.8.4TTL
The TTL output stage is a variation of a totem pole
modified to operate from an independent isolated supply
voltage from 2.7 to 5.5 V. This supply voltage is also
independent of other supply voltages used in the
UAA1570HL. Circuits to minimize cross-conductance and
short-circuit currents are provided.
Operating from a 2.7 V supply, VOL and VOH are nominally
132 mV and 1.95 V, respectively. Operating from a 5.5 V
supply, VOL and VOH are nominally 195 mV and 4.6 V,
respectively.
Typical rise times of 8 ns and fall times of 10 ns can be
expected from this output driving CMOS loads.
7.8.51The rise and fall times of the TTL output with a 15 pF load
are approximately 8 ns and are relatively independent of
supply and temperature. A small decrease (1 to 2 ns) in
rise and fall times is seen at T
increase at T
Typical propagation delay times through the time
quantization circuitry while switching amplitude
quantization states from a 5.5 V supply are:
SCLK input to TTL SIGN output 16 ns (rising edge)
SCLK input to TTL SIGN output 17.6 ns (falling edge).
7.9Programmable synthesizer
The UAA1570HL includes a programmable synthesizer
allowing the main, second LO and reference dividers to be
programmed under external control via a three-wire serial
control bus. Alternatively, a LOW on the STROBE input on
power-up will load a 20-bit default frequency plan word and
power-on options into the synthesizer registers.
Frequency plans with a 2nd IF of
4 × f
(1.023 MHz) = 4.092 MHz can be implemented.
0
7.9.1VCO
After the VCO signal leaves its single-ended-to-balanced
cascode buffer it is again amplified on its way to a high
speed fixed divide-by-2 prescaler using a super buffer
such as that described for the first mixer (see Section 7.3).
OUTPUT STAGE
BIT DELAYS
= 120 °C (2 to 4 ns).
amb
PRESCALER
= −55 °C and a small
amb
1999 May 1036
Page 37
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
7.9.2MAIN SYNTHESIZER DIVIDERS (N-PATH)
The main synthesizer divider path includes an additional
fixed divide-by-3 prescaler preceding a programmable
variable N-divider which can be programmed over a range
from 64 to 127. The output of the programmable divider
passes through a fixed divide-by-2 and finally an optional
divide-by-1 or divide-by-2 before being applied to the
phase frequency detector.
7.9.3S
The second LO signal is divided down from the VCO
prescaler output, first by a programmable L-divider and
then by a fixed divide-by-2 before being buffered and
applied to the second mixer.
7.9.4R
After squaring (limiting), the reference signal is divided
down first by a variable R-divider. The divide ratio ranges
from 4 to 31. The variable divider is followed by an optional
divide-by-1 or divide-by-2 before being applied to the
phase/frequency detector.
7.10Serial interface
The three-wire serial bus consists of DC-coupled DATA,
CLOCK and STROBE CMOS level inputs. The DATA input
loads serial 20-bit programming words into the synthesizer
data input register on each rising edge of the CLOCK
input, while the strobe line is held LOW.
The CLOCK signal should be set-up HIGH for at least
30 ns before the STROBE state is changed.
Each DATA bit should be set-up for at least 30 ns before
being clocked into the register and then held for at least
30 ns. The CLOCK rate should not exceed 10 MHz and
the CLOCK pulse width should be at least 30 ns.
The 20-bit DATA word definition follows in the order in
which they are to be read (clocked) into the DATA register.
ECOND LOCAL OSCILLATOR DIVIDERS (L-PATH)
EFERENCE DIVIDERS (R-PATH)
UAA1570HL
7.10.2r5
Next a post reference scaler bit, r5, is set to program a
divide-by-1 or divide-by-2 following the variable reference
divider. With this bit set LOW the divide-by-2 post scaler is
enabled and the phase frequency detector receives equal
mark/space ratio reference port signals. This is the default
state for this bit (r5 = 0). In the HIGH state the mark/space
ratio is a function of the variable reference divider value,
and the range of the reference divider is extended to lower
division ratios.
7.10.3r0, r1, r2, r3
The next five bits clocked into the DATA register are the
binary equivalent value of the variable reference divider
ratio. The programmable range of this divider is 4to31,continuous. The default value is set to 4
(r0, r1, r2, r3, r4 = 0, 0, 1, 0, 0) with the Most Significant
Bit (MSB) clocked into the DATA register first. The total
reference division ratio is set by these five bits if r5 is set
to the HIGH state. The range can be optionally doubled to
even values from 8 to 62 if r5 is set LOW. This option is
set in the default case, resulting in equal mark/space ratios
as described above. The total default reference division
ratio is therefore 8 with
(r0, r1, r2, r3, r4, r5 = 0, 0, 1, 0, 0, 0).
7.10.4n7
As in the reference divider case the main synthesizer
divider includes an optional post scaler divider following
the main programmable divider. This divide-by-1 or
divide-by-2 is controlled by program word bit n7. With this
bit set LOW the divide-by-2 post scaler is enabled and the
phase frequency detector receives equal mark/space ratio
signals at its main synthesizer port. The default state for
this bit is (n7 = 1) which does NOT double the total main
synthesizer divide ratio as described below.
7.10.5n0, n1, n2, n3, n4, n5
AND r4
AND n6
7.10.1p0
The first bit read into the synthesizer should be the
power-down bit, p1, which enables one of two power-down
states if set HIGH. The second bit read into the register,
p0, defines the type of power-down. A complete
power-down of the UAA1570HL is performed if this bit is
set HIGH and a partial power-down with the synthesizer
remaining on if this bit is set LOW. For normal operation of
the UAA1570HL both of these bits are set LOW, which are
also the default values for p0,p1 = 0,0. The final
p0,p1 = 1,0 state is undefined.
1999 May 1037
AND p1
The next seven bits clocked into the DATA register are the
binary equivalent value of the variable main synthesizer
divider ratio. The programmable range of this divider is
64 to 127, continuous. The default value is set to 71
(n0, n1, n2, n3, n4, n5, n6 = 1, 1, 1, 0, 0, 0, 1) with the
MSB clocked into the DATA register first. The output of the
main programmable divider includes a fixed divide-by-2
which modifies the previous range to all even values from
128 to 254, inclusive. The programmable portion of the
main synthesizer division ratio is set by these seven bits if
n7 is set to the HIGH state as described above for the
default case.
Page 38
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
This ratio can again be optionally doubled by setting n7
LOW. The range is then extended to values from
256 to 508, inclusive, in increments of 4. Equal
mark/space-ratio signals are always fed to the main
synthesizer port of the phase frequency detector since the
fixed divide-by-2 post scaler is always present. The main
synthesizer path divisions ratio range, including the fixed
divide-by-2 and divide-by-3 prescalers, is increased by a
factor of 6 from 768 to 1524 in increments of 12 when
n7 is set HIGH or from1536 to 3048 in increments of 24
if n7 is set LOW. The total default main synthesizer path
division ratio from the VCO is 12 × 71 or 852 with
(n0, n1, n2, n3, n4, n5, n6, n7 = 1, 1, 1, 0, 0, 0, 1, 1).
7.10.6l0, l1, l2
The last four bits clocked into the DATA register set the
programmable division ratio for the 2nd local oscillator.
Again the MSB is read in first with the binary word set to a
number between 4 and 15.
The default values are set to 10 (l0, l1, l2, l3 = 0, 1, 0, 1).
Again a post scaler is provided with a fixed divide-by-2
value to ensure that the LO signal exhibits equal
mark/space ratios driving the second mixer.
The programmable divider and fixed post scaler provide
division between 8 and 30 in even increments. Since the
2nd local oscillator path from the VCO includes the
divide-by-2 prescaler common to both the L-divider and
N-divider paths, the total programmable 2nd local
oscillator division range, relative to the VCO, is 16 to 60 in
increments of 4.
With the 20-bit programming word completely clocked into
the DATA register the STROBE signal is returned to a
HIGH state after a minimum delay of 30 ns to latch and
effect the parallel loading of the programmed word states.
AND l3
UAA1570HL
7.12The default frequency plan
The default synthesizer programming produces the
following frequency plan:
Table 2 Frequency plan
PARAMETERVALUE
RF input frequency1.57542GHz
VCO frequency1.5336 GHz
RF image frequency1.49178 GHz
First IF frequency41.82 MHz
Second LO division ratio2 × 10 × 2=40
Second LO frequency38.34 MHz
Second image frequency34.86 Hz
Second IF frequency3.48MHz
Reference frequency14.4 MHz
Total main synthesizer division
ratio
Total reference division ratio2 × 4=8
Phase comparison frequency1.8 MHz
7.13Phase detector, charge pump and loop filter
The phase detector is of a phase and frequency sensitive
digital type. In conjunction with the charge pump, it
operates without a ‘dead zone’.
The charge pump itself has a single-ended output
delivering or sinking current pulses with a maximum
amplitude of 240 µA into the external loop filter.
The layout for the connection between the loop filter and
the VCO input should be made with utmost care in order to
avoid other signals entering this path.
2 × 3 × 71 × 2 = 852
7.11The serial interface word
The complete default program word once serially loaded
or loaded by default on power-up with the STROBE held
LOW realizes the following frequency plan in the
UAA1570HL. It should be noted that the MSB for the
complete 20-bit program word is l0 and the Least
Significant Bit (LSB) is p1 with the latter the first loaded into
the DATA register. This is in contrast to the sequence in
which the different bits determining the individual divider
ratios are structured. The resulting default 20-bit word is:
l0, l1, l2, l3, n0, n1, n2, n3, n4, n5, n6, n7, r0, r1, r2, r3,
r4, r5, p0, p1 =
0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0.
1999 May 1038
The loop filter as chosen on the demonstration board
yields a loop bandwidth of approximately 100 kHz, with a
damping constant of 1. It consists of a 3.9 nF capacitor
and a series resistor of 20 kΩ, both in parallel with a
150 pF capacitor.
Some applications of the UAA1570HL may require the use of an external LNA. Since LNA1 is self contained and includes
independent bias circuitry, it can be powered down simply by not connecting the respective supply pin or tying it to
ground. Some considerations apply to optimize performance when using an external LNA. Generally the UAA1570HL
has been optimized with approximately 15 dB of gain in the first LNA. To prevent degradation of the system noise figure
or dynamic range in subsequent system functions, such as the first mixer or synthesizer, some limitations on the nominal
effective gain and noise figure of external devices should be taken into account. The following values are not specified,
since exceeding the recommended ranges may still result in adequate dynamic performance in some 1-bit GPS system
applications.
MX1, MX2,
1-BIT
2nd LODPLL
Note: LNA2 has to be powered-up under all circumstances, i.e. its supply pin has to be connected to V
circumstances due to biasing constraints.
Table 4 Operation with external LNAs
MAXIMUM
RECOMMENDED
MODEV
Normalyesyes10 dB−3.5 dB3.5 dB−
LNA1
replacement;
note 1
LNA1/LNA2
replacement;
notes 1 and 2
Notes
1. The maximum external noise figure listed is that which will produce approximately a 1 dB degradation in system
noise figure using the minimum recommended external gain. The maximum recommended external gain listed
results in approximately 1 dB compression in the second mixer input with an in-band continuous wave jammer
present (J/S = 35 dB) for nominal processed parts.
2. If a high gain external LNA is used, both LNA1 and LNA2 should be removed from the signal path. However, the
LNA2 supply pin has to be connected to VCC to retain power to the first mixer.
CC(LNA1)VCC(LNA2)
noyes25 dB8 dB4 dB6.5 mA
noyes41 dB21 dB4 dB6.5 mA
EXTERNAL GAIN
INCLUDING
CABLE AND
FILTER LOSSES
MINIMUM
RECOMMENDED
EXTERNAL GAIN
INCLUDING
CABLE AND
FILTER LOSSES
MAXIMUM
RECOMMENDED
EXTERNAL
NOISE FIGURE
INCLUDING
CABLE AND
FILTER LOSSES
under all
CC
INTERNAL
CURRENT
REDUCTION
1999 May 1039
Page 40
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
9LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134). All ground pins are tied together.
SYMBOLPARAMETERCONDITIONSMIN.MAX.UNIT
V
max
maximum voltage at any pin with respect to
ground
V
V
T
T
T
V
CCA
DDD
stg
j
amb
es
analog supply voltage−0.5+5.5V
digital supply voltage−0.5+5.5V
storage temperature−65+150°C
junction temperature−150°C
operating ambient temperatureV
CCA=VDDD
=5V−40+85°C
electrostatic handlingnote 1−2000+2000V
Note
1. Human body model: Equivalent to discharging a 100 pF capacitor through a 1.5 kΩ series resistor.
10 THERMAL CHARACTERISTICS
SYMBOLPARAMETERCONDITIONSVALUEUNIT
R
th(j-a)
thermal resistance from junction to ambientin free air74K/W
−0.5VCC+ 0.5 V
11 DC CHARACTERISTICS
=25±2°C; test circuit see Fig.25; unless otherwise specified.
T
amb
SYMBOLPARAMETERCONDITIONSMIN.TYP.MAX.UNIT
Supplies
I
CCA(LNA1)
I
CCA(LNA2)
I
CCA(VCO)
I
bias(MX1)
I
O(MX1)
I
bias(MX2)
LNA1 analog supply currentV
LNA2 analog supply currentV
VCO analog supply currentV
MX1 bias currentV
MX1 output current
(pins 17 and 18)
MX2 bias currentV
= 2.7 V4.276.48.23mA
CCA
V
= 3 V4.796.548.04mA
CCA
V
= 5 V5.37.158.73mA
CCA
= 2.7 V57.18.9mA
CCA
V
= 3 V5.227.269.01mA
CCA
V
= 5 V5.687.929.83mA
CCA
= 2.7 V2.853.744.64mA
CCA
V
= 3 V2.863.774.69mA
CCA
= 5 V2.893.824.76mA
V
CCA
= 2.7 V5.187.499.03mA
CCA
V
= 3 V5.367.639.13mA
CCA
V
= 5 V5.618.029.63mA
CCA
V
= 2.7 V3.844.975.77mA
CCA
= 3 V3.895.065.9mA
V
CCA
= 5 V4.065.396.33mA
V
CCA
= 2.7 V1.672.362.88mA
CCA
V
= 3 V1.692.392.92mA
CCA
= 5 V1.712.442.98mA
V
CCA
1999 May 1040
Page 41
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
SYMBOLPARAMETERCONDITIONSMIN.TYP.MAX.UNIT
I
O(MX2)
I
CCA(LIM)
I
CCA(PLL)
I
DDDL
I
DDDH
I
tot(wake)
I
tot(sleep)
I
tot(synth)
LNA1 and LNA2
V
LNAIN
V
LNAOUT
Reference input; pin 8
V
REFIN
MX2 output current
(pins 24 and 25)
LIM analog supply currentV
PLL analog supply currentV
V
= 2.7 V2.413.734.56mA
CCA
V
= 3 V2.463.794.62mA
CCA
V
= 5 V2.533.934.81mA
CCA
= 2.7 V0.91.311.53mA
CCA
V
= 3 V0.971.411.65mA
CCA
V
= 5 V1.3922.34mA
CCA
= 2.7 V11.4514.316.07mA
CCA
V
= 3 V11.6714.9817.06mA
CCA
V
= 5 V12.215.8518.13mA
CCA
LOW TTL digital current5 kΩ DC load;
V
= 2.7 V
DDD
5kΩ DC load; V
5kΩ DC load; V
HIGH TTL digital current5 kΩ DC load;
V
= 2.7 V
DDD
5kΩ DC load; V
5kΩ DC load; V
total current (wake state)V
total current (sleep state)V
total current (synthesizer state)V
DC operating point LNA1IN and
LNA2IN (pins 45 and 3)
DC operating point LNA1OUT
and LNA2OUT (pins 48 and 6)
1. The noise figure of the GPS application board is estimated from the −3 dB sensitivity testing by substitution using a
10 dB external LNA with a noise figure of less than 2 dB.
2. The sensitivity of the GPS application board is measured by recording the RF level required to observe a 3 dB drop
in the sampled L1 signal, after sampling to 1.32 MHz product [3.48 MHz(IF2) − 4.8 MHz (f
output.
3. At L1 (1.57542 GHz) with a −35 dBm input with matching components tuned at 3 V at T
4. From the matched single-ended RF mixer preamplifier input to the differential IF output of MX1.
5. From the matched single-ended RF mixer preamplifier input to the differential IF output of MX1 across an equivalent
400 Ω loading of an 800 Ω termination and transformer differential load (4 : 1 ratio to a 50 Ω measurement
termination).
6. From the matched single-ended RF input to the differential IF output of MX1 into an equivalent 400 Ω differential load.
Half of the delivered conversion gain power is delivered to an 800 Ω termination, with the remaining power
transformed (z-ratio 16 : 1) down and delivered to a 50 Ω termination. The available tabulated power is 3 dB higher
than the power delivered to the 50 Ω termination.
7. From the differential transformer matched RF input to the differential IF output of MX2.
8. From the differential transformer matched RF input to the differential IF output of MX2 across an equivalent 400 Ω
loading of an 800 Ω termination and transformer differential load (4 : 1 ratio to a 50 Ω measurement termination).
9. From the differential transformer matched RF input to the differential IF output of MX2 into an equivalent 400 Ω
differential load. Half of the delivered conversion gain power is delivered to an 800 Ω termination, with the remaining
power transformed (z-ratio 16 : 1) down and delivered to a 50 Ω termination. The available tabulated power is 3 dB
higher than the power delivered to the 50 Ω termination. The back-to-back 50 Ω : 800 Ω : 800 Ω :50Ω response
characteristics of mini circuits RF transformer T16-6T are provided in Fig.11.
10. Simulated values without external pin strays.
11. Due to test time constraints the sensitivity of the limiter is measured indirectly in the current ATE test definition. Bench
characterization using a 1 : 16 Ω ratio transformer established −3 dB limiting sensitivity at 100 µV (peak value)
across the 800 Ω terminated transformer output at the limiter input. This sensitivity is not due to gain limitations, but
rather intrinsic complex broadband noise characteristics over an estimated 800 MHz equivalent sampled spectral
bandwidth. However, the measured −82 dBm sensitivity of the device in an 800 Ω operating environment defines the
minimum level which can be detected in the sampling quantizer. The ATE test method results perform about 8.2 dBV
better than bench characterization using conventional −3 dB limiting. The specification results represent the ATE
results degraded by 8.2 dB. The limiter noise figure test is being degraded by 800 Ω transformer termination loss.
Only a weak and remote correlation exist between highly non-linear noise figure measurements made on a time
sampled quantizer output and linear simulation results.
12. The peak VCO tank swing and phase noise are measured in the default application board. With high Q resonators
the peak voltage swing at the resonator pin should be limited to <0.8 V (peak value). A de-biasing resistor can be
added from the TANK pin to ground.
amb
)] in the SIGN bit
sample
=25°C.
1999 May 1049
Page 50
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Global Positioning System (GPS) front-end
receiver circuit
PIN VOLTAGE
PINSYMBOL
40COMPdepends on
TYPICAL VALUES (V)
V
= 2.7 VVCC=5V
CC
depends on
VCO
application
VCO
application
41P41GND00
42P42GND00
43V
CCA(LNA1)
2.75
44LNA1GND100
45LNA1IN0.8150.807
EQUIVALENT CIRCUIT WITHOUT ESD PROTECTION
UAA1570HL
CIRCUITS
40
MHB315
45
46BIASGND100
47LNA1GND200
48LNA1OUT1.483.629
44
MHB316
48
47
MHB317
1999 May 1071
Page 72
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
16 PACKAGE OUTLINE
LQFP48: plastic low profile quad flat package; 48 leads; body 7 x 7 x 1.4 mm
c
y
X
36
37
25
Z
24
E
A
UAA1570HL
SOT313-2
e
w M
pin 1 index
48
1
e
DIMENSIONS (mm are the original dimensions)
mm
A
A1A2A3bpcE
max.
0.20
0.05
1.45
1.35
1.60
UNIT
Note
1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
b
p
0.25
w M
D
H
D
0.27
0.17
12
Z
D
(1)(1)(1)
D
0.18
7.1
0.12
6.9
b
p
13
v M
B
v M
02.55 mm
scale
(1)
eH
H
D
7.1
6.9
0.5
9.15
8.85
E
A
B
9.15
8.85
H
E
LL
E
0.75
0.45
A
p
A
2
A
1
L
detail X
Z
D
0.120.10.21.0
0.95
0.55
(A )
3
L
p
Zywvθ
E
0.95
0.55
θ
o
7
o
0
OUTLINE
VERSION
SOT313-2
IEC JEDEC EIAJ
REFERENCES
1999 May 1072
EUROPEAN
PROJECTION
ISSUE DATE
94-12-19
97-08-01
Page 73
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
17 SOLDERING
17.1Introduction to soldering surface mount
packages
This text gives a very brief insight to a complex technology.
A more in-depth account of soldering ICs can be found in
our
“Data Handbook IC26; Integrated Circuit Packages”
(document order number 9398 652 90011).
There is no soldering method that is ideal for all surface
mount IC packages. Wave soldering is not always suitable
for surface mount ICs, or for printed-circuit boards with
high population densities. In these situations reflow
soldering is often used.
17.2Reflow soldering
Reflow soldering requires solder paste (a suspension of
fine solder particles, flux and binding agent) to be applied
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.
Several methods exist for reflowing; for example,
infrared/convection heating in a conveyor type oven.
Throughput times (preheating, soldering and cooling) vary
between 100 and 200 seconds depending on heating
method.
Typical reflow peak temperatures range from
215 to 250 °C. The top-surface temperature of the
packages should preferable be kept below 230 °C.
UAA1570HL
If wave soldering is used the following conditions must be
observed for optimal results:
• Use a double-wave soldering method comprising a
turbulent wave with high upward pressure followed by a
smooth laminar wave.
• For packages with leads on two sides and a pitch (e):
– larger than or equal to 1.27mm, the footprint
longitudinal axis is preferred to be parallel to the
transport direction of the printed-circuit board;
– smaller than 1.27mm, the footprint longitudinal axis
must be parallel to the transport direction of the
printed-circuit board.
The footprint must incorporate solder thieves at the
downstream end.
• For packages with leads on four sides, the footprint must
be placed at a 45° angle to the transport direction of the
printed-circuit board. The footprint must incorporate
solder thieves downstream and at the side corners.
During placement and before soldering, the package must
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the
adhesive is cured.
Typical dwell time is 4 seconds at 250 °C.
A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.
17.3Wave soldering
Conventional single wave soldering is not recommended
for surface mount devices (SMDs) or printed-circuit boards
with a high component density, as solder bridging and
non-wetting can present major problems.
To overcome these problems the double-wave soldering
method was specifically developed.
1999 May 1073
17.4Manual soldering
Fix the component by first soldering two
diagonally-opposite end leads. Use a low voltage (24 V or
less) soldering iron applied to the flat part of the lead.
Contact time must be limited to 10 seconds at up to
300 °C.
When using a dedicated tool, all other leads can be
soldered in one operation within 2 to 5 seconds between
270 and 320 °C.
Page 74
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
UAA1570HL
receiver circuit
17.5Suitability of surface mount IC packages for wave and reflow soldering methods
1. All surface mount (SMD) packages are moisture sensitive. Depending upon the moisture content, the maximum
2. These packages are not suitable for wave soldering as a solder joint between the printed-circuit board and heatsink
3. If wave soldering is considered, then the package must be placed at a 45° angle to the solder wave direction.
4. Wave soldering is only suitable for LQFP, TQFP and QFP packages with a pitch (e) equal to or larger than 0.8 mm;
5. Wave soldering is only suitable for SSOP and TSSOP packages with a pitch (e) equal to or larger than 0.65 mm; it is
, SOsuitablesuitable
temperature (with respect to time) and body size of the package, there is a risk that internal or external package
cracks may occur due to vaporization of the moisture in them (the so called popcorn effect). For details, refer to the
Drypack information in the
(at bottom version) can not be achieved, and as solder may stick to the heatsink (on top version).
The package footprint must incorporate solder thieves downstream and at the side corners.
it is definitely not suitable for packages with a pitch (e) equal to or smaller than 0.65 mm.
definitely not suitable for packages with a pitch (e) equal to or smaller than 0.5 mm.
Objective specificationThis data sheet contains target or goal specifications for product development.
Preliminary specificationThis data sheet contains preliminary data; supplementary data may be published later.
Product specificationThis data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
19 LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
1999 May 1074
Page 75
Philips SemiconductorsProduct specification
Global Positioning System (GPS) front-end
receiver circuit
NOTES
UAA1570HL
1999 May 1075
Page 76
Philips Semiconductors – a worldwide company
Argentina: see South America
Australia: 34 Waterloo Road, NORTH RYDE, NSW 2113,
United States: 811 East Arques Avenue, SUNNYVALE, CA 94088-3409,
Tel. +1 800 234 7381, Fax. +1 800 943 0087
Uruguay: see South America
Vietnam: see Singapore
Yugoslavia: PHILIPS, Trg N. Pasica 5/v, 11000 BEOGRAD,
Tel. +381 11 62 5344, Fax.+381 11 63 5777
For all other countries apply to: Philips Semiconductors,
International Marketing & Sales Communications, Building BE-p, P.O. Box 218,
5600 MD EINDHOVEN, The Netherlands, Fax. +31 40 27 24825
The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed
without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license
under patent- or other industrial or intellectual property rights.
199964
Internet: http://www.semiconductors.philips.com
Printed in The Netherlands285002/00/01/pp76 Date of release: 1999 May 10Document order number: 9397 750 04463
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