Page 1
RF COMMUNICATIONS PRODUCTS
SA625
High performance low power mixer FM IF
system with high-speed RSSI
Product specification
Replaces data of November 3, 1992
IC17 Data Handbook
Philips Semiconductors
1997 Nov 07
Page 2
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
DESCRIPTION
The SA625 is pin-to-pin compatible with the SA605, but has faster
RSSI rise and fall times. The SA625 is a high performance
monolithic low-power FM IF system incorporating a mixer/oscillator,
two limiting intermediate frequency amplifiers, quadrature detector,
muting, logarithmic received signal strength indicator (RSSI) with
fast rise and fall time, and voltage regulator. The SA625 combines
the functions of Signetics’ SA602A and SA624. The SA625 is
available in 20-lead SSOP (shrink small outline package).
For additional technical information please refer to application notes
AN1994, 1995 and 1996, which include example application
diagrams, a complete overview of the product and artwork for
reference.
FEATURES
•Fast RSSI rise and fall times
•Low power consumption: 5.8mA typical at 6V
•Mixer input to >500MHz
•Mixer conversion power gain of 13dB at 45MHz
•Mixer noise figure of 4.6dB at 45MHz
•XTAL oscillator effective to 150MHz (L.C. oscillator to 1GHz local
oscillator can be injected)
•102dB of IF Amp/Limiter gain
•25MHz limiter small signal bandwidth
•Temperature compensated logarithmic Received Signal Strength
Indicator (RSSI) with a dynamic range in excess of 90dB
•Two audio outputs - muted and unmuted
•Low external component count; suitable for crystal/ceramic/LC
filters
•Excellent sensitivity: 0.22µV into 50Ω matching network for 12dB
SINAD (Signal to Noise and Distortion ratio) for 1kHz tone with RF
at 45MHz and IF at 455kHz
•SA625 meets cellular radio specifications
PIN CONFIGURATION
MUTED AUDIO OUT
UNMUTED AUDIO OUT
QUADRATURE IN
•ESD hardened
APPLICA TIONS
•Digital cellular base stations
•High performance communications receivers
•Single conversion VHF/UHF receivers
•SCA receivers
•RF level meter
•Spectrum analyzer
•Instrumentation
•FSK and ASK data receivers
•Log amps
•Wideband low current amplification
•Digital cordless telephones
DK Package
RF
1
IN
RF BYPASS 2
XTAL OSC 3
XTAL OSC 4
MUTE
5
IN
6
V
CC
RSSI
7
OUT
8
9
10
Figure 1. Pin Configuration
20 MIXER OUT
19
IF AMP DECOUPLING
18 IF AMP IN
17
IF AMP DECOUPLING
16 IF AMP OUT
15 GND
14 LIMITER IN
13
LIMITER DECOUPLING
12
LIMITER DECOUPLING
11 LIMITER OUT
SA625
SR00456
ORDERING INFORMATION
DESCRIPTION TEMPERATURE RANGE ORDER CODE DWG #
20-Pin Plastic Shrink Small Outline Package (SSOP) (Surface-mount) -40 to +85°C SA625DK
1997 Nov 07 853-1648 18664
2
SOT266-1
Page 3
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
BLOCK DIAGRAM
20 19 18 17 16 15 14 13 12 11
IF
AMP
OSCILLATOR
EB
Figure 2. Block Diagram
SA625
LIMITER
RSSI
10987654321
SR00457
ABSOLUTE MAXIMUM RATINGS
SYMBOL PARAMETER RATING UNITS
T
V
θ
CC
STG
T
A
JA
Single supply voltage 9 V
Storage temperature range -65 to +150
Operating ambient temperature range SA625 -40 to +85
Thermal impedance DK package 117
°C/W
°C
°C
DC ELECTRICAL CHARACTERISTICS
VCC = +6V, TA = 25°C; unless otherwise stated.
LIMITS
SYMBOL PARAMETER TEST CONDITIONS SA625 UNITS
MIN TYP MAX
V
CC
I
CC
Power supply voltage range 4.5 8.0 V
DC current drain 4.55 5.8 6.75 mA
Mute switch input threshold
(ON)
(OFF) 1.0 V
1.7 V
1997 Nov 07
3
Page 4
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
AC ELECTRICAL CHARACTERISTICS
TA = 25°C; VCC = +6V, unless otherwise stated. RF frequency = 45MHz + 14.5dBV RF input step-up; IF frequency = 455kHz; R17 = 5.1k; RF
level = -45dBm; FM modulation = 1kHz with ±8kHz peak deviation. Audio output with C-message weighted filter and de-emphasis capacitor.
Test circuit Figure 3. The parameters listed below are tested using automatic test equipment to assure consistent electrical characterristics.
The limits do not represent the ultimate performance limits of the device. Use of an optimized RF layout will improve many of the listed parameters.
LIMITS
SYMBOL PARAMETER TEST CONDITIONS
MIN TYP MAX
Mixer/Osc section (ext LO = 300mV)
f
IN
f
OSC
IF section
THD Total harmonic distortion -34 -42 dB
S/N Signal-to-noise ratio No modulation for noise 73 dB
Input signal frequency 500 MHz
Crystal oscillator frequency 150 MHz
Noise figure at 45MHz 5.0 dB
Third-order input intercept point f1 = 45.0; f2 = 45.06MHz -10 dBm
Conversion power gain Matched 14.5dBV step-up 10 13 15 dB
50Ω source -1.7 dB
RF input resistance Single-ended input 3.0 4.7 kΩ
RF input capacitance 3.5 4.0 pF
Mixer output resistance (Pin 20) 1.25 1.5 kΩ
IF amp gain 50Ω source 39.7 dB
Limiter gain 50Ω source 62.5 dB
Input limiting -3dB, R17 = 5.1k Test at Pin 18 -113 dBm
AM rejection 80% AM 1kHz 29 34 43 dB
Audio level, R10 = 100k 15nF de-emphasis 80 150 260 mV
Unmuted audio level, R11 = 100k 150pF de-emphasis 480 mV
SINAD sensitivity RF level -118dB 16 dB
IF RSSI output, R9 = 100kΩ
IF RSSI output rise time RF level = -28dBm 1.2 µs
(10kHz pulse, no 455kHz filter) IF frequency = 10.7MHz
(no RSSI bypass capacitor) RF level = -56dBm 1.2 µs
IF RSSI output fall time RF level = -28dBm 7.6 µs
(10kHz pulse, no 455kHz filter) IF frequency = 10.7MHz
(no RSSI bypass capacitor) RF level = -56dBm 2.0 µs
RSSI range R9 = 100kΩ Pin 16 90 dB
RSSI accuracy R9 = 100kΩ Pin 16 +1.5 dB
IF input impedance 1.40 1.6 kΩ
IF output impedance 0.85 1.0 kΩ
Limiter intput impedance 1.40 1.6 kΩ
Limiter output impedance 300 Ω
Limiter output level with no load 280 mV
1
IF level = -118dBm 0 160 650 mV
IF level = -68dBm 1.9 2.5 3.1 V
IF level = -18dBm 4.0 4.8 5.6 V
IF frequency = 455kHz
RF level = -56dBm 1.2 µs
RF level = -28dBm 1.1 µs
IF frequency = 455kHz
RF level = -56dBm 2.1 µs
RF level = -28dBm 7.3 µs
SA625
SA625
UNITS
RMS
RMS
1997 Nov 07
4
Page 5
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
AC ELECTRICAL CHARACTERISTICS(Continued)
LIMITS
SYMBOL PARAMETER TEST CONDITIONS SA625 UNITS
MIN TYP MAX
IF section (continued)
Unmuted audio output resistance 58 kΩ
Muted audio output resistance 58 kΩ
RF/IF section (int LO)
Unmuted audio level 4.5V = VCC, RF level = -27dBm 450 mV
System RSSI output 4.5V = VCC, RF level = -27dBm 4.3 V
NOTE:
1. The generator source impedance is 50Ω, but the SA625 input impedance at Pin 18 is 1500Ω. As a result, IF level refers to the actual signal
that enters the SA625 input (Pin 8) which is about 21dB less than the ”available power” at the generator.
CIRCUIT DESCRIPTION
The SA625 is an IF signal processing system suitable for second IF
or single conversion systems with input frequency as high as 1GHz.
The bandwidth of the IF amplifier is about 40MHz, with 39.7dB(v) of
gain from a 50Ω source. The bandwidth of the limiter is about
28MHz with about 62.5dB(v) of gain from a 50Ω source. However,
the gain/bandwidth distribution is optimized for 455kHz, 1.5kΩ
source applications. The overall system is well-suited to battery
operation as well as high performance and high quality products of
all types.
The input stage is a Gilbert cell mixer with oscillator. Typical mixer
characteristics include a noise figure of 5dB, conversion gain of
13dB, and input third-order intercept of -10dBm. The oscillator will
operate in excess of 1GHz in L/C tank configurations. Hartley or
Colpitts circuits can be used up to 100MHz for xtal configurations.
Butler oscillators are recommended for xtal configurations up to
150MHz.
The output of the mixer is internally loaded with a 1.5kΩ resistor
permitting direct connection to a 455kHz ceramic filter. The input
resistance of the limiting IF amplifiers is also 1.5kΩ. With most
455kHz ceramic filters and many crystal filters, no impedance
matching network is necessary. To achieve optimum linearity of the
log signal strength indicator , there must be a 12dB(v) insertion loss
between the first and second IF stages. If the IF filter or interstage
network does not cause 12dB(v) insertion loss, a fixed or variable
resistor can be added between the first IF output (Pin 16) and the
interstage network.
The signal from the second limiting amplifier goes to a Gilbert cell
quadrature detector . One port of the Gilbert cell is internally driven
by the IF. The other output of the IF is AC-coupled to a tuned
quadrature network. This signal, which now has a 90
relationship to the internal signal, drives the other port of the
multiplier cell.
Overall, the IF section has a gain of 90dB. For operation at
intermediate frequencies greater than 455kHz, special care must be
given to layout, termination, and interstage loss to avoid instability.
The demodulated output of the quadrature detector is available at
two pins, one continuous and one with a mute switch. Signal
attenuation with the mute activated is greater than 60dB. The mute
input is very high impedance and is compatible with CMOS or TTL
levels.
A log signal strength completes the circuitry. The output range is
greater than 90dB and is temperature compensated. This log signal
strength indicator exceeds the criteria for AMPs or TACs cellular
telephone.
NOTE: dB(v) = 20log V
OUT/VIN
SA625
RMS
° phase
1997 Nov 07
5
Page 6
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
-25dB,
1500/50
50.5
3880
Ω PAD
SW9
20
-10dB,
50/50
Ω PAD
96.5
2430
32.6
C24 C22
FLT1
C23
71.5
SW8
-29dB,
929/50
51.5
C21
Ω PAD
C20
SW7
19 18 17 16 15 14
IF AMP
MIXER
OSCILLATOR
EMITTER BASE
700
R17
5.1k
-10.6dB,
50/50
96.5
32.8
FLT2
LIMITER
RSSI
-36dB,
Ω PAD
71.5
C19
SW6 SW5
C18
156k/50
51.7
C17
13 12 11
QUAD
DETECTOR
MUTE
SWITCH
Ω PAD
1.3k
C16
SA625
C15
C1
L1
C2
R4
51.1
SW2
R1
C3
R2
R3
45MHZ
MINI–CIRCUIT ZSC2–1B
C4
C5
EXT.
LOC
OSC
44.545
SW3 SW4SW1
C8
C7
L2
R6
178
R7
30.5
X1
C6
45.06
MHZ
Automatic Test Circuit Component List
100pF NPO Ceramic
C1
390pF NPO Ceramic
C2
C5
100nF ±
10% Monolithic Ceramic
22pF NPO Ceramic
C6
1nF Ceramic
C7
10.0pF NPO Ceramic
C8
C9
C10
C11
C12
C13
C14
C15
C17
C18
*NOTE: This value can be reduced when a battery is the power source.
10% Monolithic Ceramic
100nF ±
6.8µF Tantalum (minimum) *
100nF ±
10% Monolithic Ceramic
15nF ±
10% Ceramic
150pF ±
2% N1500 Ceramic
10% Monolithic Ceramic
100nF ±
10pF NPO Ceramic
10% Monolithic Ceramic
100nF ±
100nF ±10% Monolithic Ceramic
Figure 3. SA625 45MHz Test Circuit (Relays as shown)
C9
R9 R10 R11
R8
39.2
MUTE RSSI
V
CC
C21
C23
C25
Flt 1
Flt 2
IFT 1
L1
L2
X1
R9
R17
R10
R11
10987654321
C13C12C11C10
IFT1
”C” WEIGHTED
AUDIO
MEASUREMENT
CIRCUIT
OUTPUT
100nF ±
100nF ±
100nF ±
AUDIO UNMUTED
AUDIO
10% Monolithic Ceramic
10% Monolithic Ceramic
10% Monolithic Ceramic
C14
Ceramic Filter Murata SFG455A3 or equiv
Ceramic Filter Murata SFG455A3 or equiv
455kHz (Ce = 180pF) Toko RMC–2A6597H
147–160nH Coilcraft UNI–10/142–04J08S
0.8µH nominal
Toko 292CNS–T1038Z
44.545MHz Crystal ICM4712701
100k ±
1% 1/4W Metal Film
5.1k ±
5% 1/4W Carbon Composition
1% 1/4W Metal Film (optional)
100k ±
100k ±
1% 1/4W Metal Film (optional)
SR00458
1997 Nov 07
6
Page 7
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
R17
5.1k
FLT1
C23
20
19 18 17 16 15 14
IF AMP
MIXER
OSCILLATOR
C21
700
FLT2
LIMITER
RSSI
C18
C17
13 12 11
QUAD
DETECTOR
MUTE
SWITCH
SA625
C15
C1
L1
C2
45MHz
INPUT
100pF NPO Ceramic
C1
390pF NPO Ceramic
C2
C5
100nF ±
10% Monolithic Ceramic
22pF NPO Ceramic
C6
1nF Ceramic
C7
10.0pF NPO Ceramic
C8
C9
C10
C11
C12
C13
C14
C15
C17
C18
10% Monolithic Ceramic
100nF ±
6.8µF Tantalum (minimum) *
100nF ±
10% Monolithic Ceramic
15nF ±
10% Ceramic
150pF ±
2% N1500 Ceramic
10% Monolithic Ceramic
100nF ±
10pF NPO Ceramic
10% Monolithic Ceramic
100nF ±
100nF ±10% Monolithic Ceramic
R5
C5
10987654321
C9
R9 R10 R11
C8
C7
L2
C6
X1
C25
MUTE RSSI
V
CC
OUTPUT
C13C12C11C10
AUDIO UNMUTED
AUDIO
IFT1
C14
Application Component List
C21
C23
C25
Flt 1
Flt 2
IFT 1
L1
L2
10% Monolithic Ceramic
100nF ±
10% Monolithic Ceramic
100nF ±
100nF ±
10% Monolithic Ceramic
Ceramic Filter Murata SFG455A3 or equiv
Ceramic Filter Murata SFG455A3 or equiv
455kHz (Ce = 180pF) Toko RMC–2A6597H
147–160nH Coilcraft UNI–10/142–04J08S
µH nominal
0.8
Toko 292CNS–T1038Z
X1
44.545MHz Crystal ICM4712701
R9
100k ±
1% 1/4W Metal Film
R17
5.1k ±
5% 1/4W Carbon Composition
Not Used in Application Board (see Note 8)
R5
R10
100k ±1% 1/4W Metal Film (optional)
R11
100k ±
1% 1/4W Metal Film (optional)
1997 Nov 07
*NOTE: This value can be reduced when a battery is the power source.
Figure 4. SA625 45MHz Application Circuit
SR00459
7
Page 8
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
RF GENERATOR
45MHz
V
(+6)
CC
Figure 5. SA625 Application Circuit Test Set Up
RSSI AUDIO DATA
DC VOLTMETER
NE625 DEMO BOARD
SCOPE
C–MESSAGE
HP339A DISTORTION
ANALYZER
SA625
SR00460
NOTES:
1. C-message: The C-message filter has a peak gain of 100 for accurate measurements. Without the gain, the measurements may be
affected by the noise of the scope and HP339 analyzer.
2. Ceramic filters: The ceramic filters can be 30kHz SFG455A3s made by Murata which have 30kHz IF bandwidth (they come in blue), or
16kHz CFU455Ds, also made by Murata (they come in black). All of our specifications and testing are done with the more wideband filter.
3. RF generator: Set your RF generator at 45.000MHz, use a 1kHz modulation frequency and a 6kHz deviation if you use 16kHz filters, or
8kHz if you use 30kHz filters.
4. Sensitivity: The measured typical sensitivity for 12dB SINAD should be 0.22µV or -120dBm at the RF input.
5. Layout: The layout is very critical in the performance of the receiver. We highly recommend our demo board layout.
6. RSSI: The smallest RSSI voltage (i.e., when no RF input is present and the input is terminated) is a measure of the quality of the layout and
design. If the lowest RSSI voltage is 250mV or higher, it means the receiver is in regenerative mode. In that case, the receiver sensitivity
will be worse than expected.
7. Supply bypass and shielding: All of the inductors, the quad tank, and their shield must be grounded. A 10-15µF or higher value tantalum
capacitor on the supply line is essential. A low frequency ESR screening test on this capacitor will ensure consistent good sensitivity in
production. A 0.1µF bypass capacitor on the supply pin, and grounded near the 44.545MHz oscillator improves sensitivity by 2-3dB.
8. R5 can be used to bias the oscillator transistor at a higher current for operation above 45MHz. Recommended value is 22kΩ, but should not
be below 10kΩ.
1997 Nov 07
8
Page 9
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
20
0
–20
–40
–60
RELATIVE TO AUDIO OUTPUT (dB)
–80
RSSI
(Volts)
AUDIO REF = 174mV
RMS
+
THD NOISE
AM (80%)
NOISE
RF = 45MHz
IF = 455kHz
= 6V
V
CC
5
4
3
2
1
RSSI
(Volts)
SA625
–100
–130 –110 –90 –70 –50 –30 –10 10
RF INPUT LEVEL (dBm)
Figure 6. SA625 Application Board at 25°C
0
SR00461
1997 Nov 07
9
Page 10
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
TOP SILK SCREEN TOP VIEW
SA625
1.6 in.
1.7 in.
BOTTOM VIEW
Figure 7. SA625 SSOP Demo-board Layout (Not Actual Size)
SR00465
1997 Nov 07
10
Page 11
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
1.70
1.65
1.60
1.55
1.50
µ
1.45
1.40
1.35
RSSI RISE TIME ( s)
1.30
1.25
1.20
1.15
1.10
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
Figure 8. SA625 Rise Time 455kHz IF Frequency
SA625
RFINP–38dBm
RFINP–28dBm
RFINP–56dBm
SR00466
8.0
7.5
7.0
6.5
6.0
µ
5.5
5.0
4.5
4.0
3.5
RSSI FALL TIME ( s)
3.0
2.5
2.0
1.5
1.0
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
RFINP–28dBm
RFINP–38dBm
RFINP–56dBm
Figure 9. SA625 Fall Time 455kHz IF Frequency
SR00467
1997 Nov 07
11
Page 12
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
1.65
1.60
1.55
1.50
µ
1.45
1.40
1.35
RSSI RISE TIME ( s)
1.30
1.25
1.20
1.15
1.10
1.00
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
Figure 10. SA625 Rise Time 10.7MHz IF Frequency
RFINP–56dBm
RFINP–28dBm
RFINP–38dBm
SA625
SR00468
8.0
7.5
7.0
6.5
6.0
µ
5.5
5.0
4.5
4.0
3.5
RSSI FALL TIME ( s)
3.0
2.5
2.0
1.5
1.0
–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
RFINP–28dBm
RFINP–38dBm
RFINP–56dBm
Figure 11. SA625 Fall T ime 10.7MHz IF Frequency
SR00469
1997 Nov 07
12
Page 13
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
SSOP20: plastic shrink small outline package; 20 leads; body width 4.4 mm SOT266-1
SA625
1997 Nov 07
13
Page 14
Philips Semiconductors Product specification
High performance low power mixer FM IF system
with high-speed RSSI
DEFINITIONS
SA625
Data Sheet Identification Product Status Definition
Objective Specification
Preliminary Specification
Product Specification
Philips Semiconductors and Philips Electronics North America Corporation reserve the right to make changes, without notice, in the products,
including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips
Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright,
or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask
work right infringement, unless otherwise specified. Applications that are described herein for any of these products are for illustrative purposes
only. Philips Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing
or modification.
LIFE SUPPORT APPLICA TIONS
Philips Semiconductors and Philips Electronics North America Corporation Products are not designed for use in life support appliances, devices,
or systems where malfunction of a Philips Semiconductors and Philips Electronics North America Corporation Product can reasonably be expected
to result in a personal injury. Philips Semiconductors and Philips Electronics North America Corporation customers using or selling Philips
Semiconductors and Philips Electronics North America Corporation Products for use in such applications do so at their own risk and agree to fully
indemnify Philips Semiconductors and Philips Electronics North America Corporation for any damages resulting from such improper use or sale.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Formative or in Design
Preproduction Product
Full Production
This data sheet contains the design target or goal specifications for product development. Specifications
may change in any manner without notice.
This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips
Semiconductors reserves the right to make changes at any time without notice in order to improve design
and supply the best possible product.
This data sheet contains Final Specifications. Philips Semiconductors reserves the right to make changes
at any time without notice, in order to improve design and supply the best possible product.
Copyright Philips Electronics North America Corporation 1997
All rights reserved. Printed in U.S.A.
1997 Nov 07
14
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