Philips sa5219 DATASHEETS
INTEGRATED CIRCUITS
SA5219
Wideband variable gain amplifier
Product specification
Replaces data of 1993 Dec 10
IC17 Data Handbook
Philips Semiconductors
1997 Nov 07
Philips Semiconductors Product specification
SA5219Wideband variable gain amplifier
DESCRIPTION
The SA5219 represents a breakthrough in monolithic amplifier
design featuring several innovations. This unique design has
combined the advantages of a high speed bipolar process with the
proven Gilbert architecture.
The SA5219 is a linear broadband RF amplifier whose gain is
controlled by a single DC voltage. The amplifier runs off a single 5
volt supply and consumes only 40mA. The amplifier has high
impedance (1kΩ) differential inputs. The output is 50Ω differential.
Therefore, the 5219 can simultaneously perform AGC, impedance
transformation, and the balun functions.
The dynamic range is excellent over a wide range of gain setting.
Furthermore, the noise performance degrades at a comparatively
slow rate as the gain is reduced. This is an important feature when
building linear AGC systems.
FEA TURES
•700MHz bandwidth
•High impedance differential input
•50Ω differential output
•Single 5V power supply
•0 - 1V gain control pin
•>60dB gain control range at 200MHz
•26dB maximum gain differential
•Exceptional V
CONTROL
/ V
GAIN
linearity
•7dB noise figure minimum
•Full ESD protection
•Easily cascadable
PIN CONFIGURATION
N, D PACKAGES
1
V
CC1
2
GND
1
3
IN
A
4
GND
1
5
IN
B
6
GND
1
7
V
BG
8
V
AGC
Figure 1. Pin Configuration
APPLICATIONS
•Linear AGC systems
•Very linear AM modulator
•RF balun
•Cable TV multi-purpose amplifier
•Fiber optic AGC
•RADAR
•User programmable fixed gain block
•Video
•Satellite receivers
•Cellular communications
16
V
15
GND
14
OUT
13
GND
12
OUT
11
GND
10
GND
9
GND
SR00273
CC2
2
A
2
B
2
2
2
ORDERING INFORMATION
Description Temperature Range Order Code DWG #
16-Pin Plastic Small Outline (SO) package -40 to +85°C SA5219D SOT109-1
16-Pin Plastic Dual In-Line package (DIP) -40 to +85°C SA5219N SOT38-4
1997 Nov 07 853-1724 18663
2
Philips Semiconductors Product specification
SYMBOL
PARAMETER
TEST CONDITIONS
UNIT
SA5219Wideband variable gain amplifier
ABSOLUTE MAXIMUM RATINGS
SYMBOL PARAMETER RATING UNITS
V
CC
P
D
T
JMAX
T
STG
NOTES:
1. Maximum dissipation is determined by the operating ambient temperature and the thermal resistance, θ
16-Pin DIP: θ
16-Pin SO: θ
RECOMMENDED OPERATING CONDITIONS
SYMBOL PARAMETER RATING UNITS
V
CC
T
A
T
J
Supply voltage -0.5 to +8.0 V
Power dissipation, TA = 25oC (still air)
16-Pin Plastic DIP
16-Pin Plastic SO
1
1450
1100
mW
mW
Maximum operating junction temperature 150
Storage temperature range -65 to +150
:
= 85°C/W
JA
= 110°C/W
JA
Supply voltage V
CC1
JA
= V
= 4.5 to 7.0V V
CC2
Operating ambient temperature range
SA Grade -40 to +85
Operating junction temperature range
SA Grade -40 to +105
°C
°C
°C
°C
DC ELECTRICAL CHARACTERISTICS
TA = 25oC, V
R
V
I
A
A
R
OUT
V
V
OUT
CC1
CC
V
V
IN
OS
IN
PSRR Output offset supply rejection ratio 18 45 dB
V
BG
R
BG
V
AGC
I
BAGC
= V
CC2
= +5V, V
= 1.0V , unless otherwise specified.
AGC
LIMITS
MIN TYP MAX
Supply current DC tested 36 43 50 mA
Voltage gain (single-ended in/single-ended out) DC tested, RL = 10kΩ 16 19 22 dB
Voltage gain (single-ended in/differential out) DC tested, RL = 10kΩ 22 25 28 dB
Input resistance (single-ended) DC tested at ±50µA 0.8 1.2 1.6 kΩ
Output resistance (single-ended) DC tested at ±1mA 35 60 80 Ω
Output offset voltage (output referred) +20 ±150 mV
DC level on inputs 1.6 2.0 2.4 V
DC level on outputs 1.9 2.4 2.9 V
Bandgap reference voltage
4.5V<VCC<7V
RBG = 10kΩ
1.2 1.32 1.45 V
Bandgap loading 2 10
AGC DC control voltage range 0-1.3 V
AGC pin DC bias current 0V<V
<1.3V -0.7 -6 µA
AGC
kΩ
1997 Nov 07
3
Philips Semiconductors Product specification
SYMBOL
PARAMETER
TEST CONDITIONS
UNIT
V
SA5219Wideband variable gain amplifier
AC ELECTRICAL CHARACTERISTICS
TA = 25oC, V
BW -3dB bandwidth 700 MHz
GF Gain flatness DC - 500MHz +0.4 dB
V
IMAX
OMAX
NF Noise figure (unmatched configuration) RS = 50Ω, f = 50MHz 9.3 dB
V
IN-EQ
S12 Reverse isolation f = 100MHz -60 dB
∆G/∆V
∆G/∆T Gain temperature sensitivity RL = 50Ω 0.013
C
IN
BW
AGC
P
O-1dB
P
I-1dB
IP3
OUT
IP3
IN
∆G
AB
NOTE:
1. With R
occurs at input for single-ended gain < 6dB and at output for single-ended gain > 6dB.
SA5219 APPLICATIONS
The SA5219 is a wideband variable gain amplifier (VGA) circuit
which finds many applications in the RF, IF and video signal
processing areas. This application note describes the operation of
the circuit and several applications of the VGA. The simplified
equivalent schematic of the VGA is shown in Figure 2. Transistors
Q1-Q6 form the wideband Gilbert multiplier input stage which is
biased by current source I1. The top differential pairs are biased
from a buffered and level-shifted signal derived from the V
and the RF input appears at the lower differential pair. The circuit
topology and layout offer low input noise and wide bandwidth. The
second stage is a differential transimpedance stage with current
feedback which maintains the wide bandwidth of the input stage.
The output stage is a pair of emitter followers with 50Ω output
impedance. There is also an on-chip bandgap reference with
buffered output at 1.3V, which can be used to derive the gain control
voltage.
Both the inputs and outputs should be capacitor coupled or DC
isolated from the signal sources and loads. Furthermore, the two
inputs should be DC isolated from each other and the two outputs
should likewise be DC isolated from each other. The SA5219 was
designed to provide optimum performance from a 5V power source.
However, there is some range around this value (4.5 - 7V) that can
be used.
The input impedance is about 1kΩ. The main advantage to a
differential input configuration is to provide the balun function.
= V
CC1
= +5.0V, V
CC2
= 1.0V , unless otherwise specified.
AGC
LIMITS
MIN TYP MAX
Maximum input voltage swing (single-ended) for
linear operation
Maximum output voltage swing (single-ended)
for linear operation
1
RL = 50Ω 400 mV
1
RL = 1kΩ 1.9 V
Equivalent input noise voltage spectral density f = 100MHz 2.5
Gain supply sensitivity (single-ended) 0.3 dB/V
CC
200 mV
nV/√Hz
dB/°C
Input capacitance (single-ended) 2 pF
-3dB bandwidth of gain control function 20 MHz
1dB gain compression point at output f = 100MHz -3 dBm
1dB gain compression point at input
Third-order intercept point at output
Third-order intercept point at input
f = 100MHz, V
f = 100MHz, V
f = 100MHz, V
Gain match output A to output B f = 100MHz, V
> 1kΩ, overload occurs at input for single-ended gain < 13dB and at output for single-ended gain > 13dB. With RL = 50Ω, overload
L
=0.1V
>0.5V
<0.5V
AGC
AGC
AGC
= 1V 0.1 dB
AGC
-10 dBm
+13 dBm
+5 dBm
Otherwise, there is an advantage to common mode rejection, a
specification that is not normally important to RF designs. The
source impedance can be chosen for two different performance
characteristics: Gain, or noise performance. Gain optimization will
be realized if the input impedance is matched to about 1kΩ. A 4:1
balun will provide such a broadband match from a 50Ω source.
Noise performance will be optimized if the input impedance is
matched to about 200Ω. A 2:1 balun will provide such a broadband
AGC
input
match from a 50Ω source. The minimum noise figure can then be
expected to be about 7dB. Maximum gain will be about 23dB for a
single-ended output. If the differential output is used and properly
matched, nearly 30dB can be realized. With gain optimization, the
noise figure will degrade to about 8dB. With no matching unit at the
input, a 9dB noise figure can be expected from a 50Ω source. If the
source is terminated, the noise figure will increase to about 15dB.
All these noise figures will occur at maximum gain.
The SA5219 has an excellent noise figure vs gain relationship. With
any VGA circuit, the noise performance will degrade with decreasing
gain. The 5219 has about a 1.2dB noise figure degradation for
each 2dB gain reduction. With the input matched for optimum gain,
the 8dB noise figure at 23dB gain will degrade to about a 20dB
noise figure at 0dB gain.
The SA5219 also displays excellent linearity between voltage gain
and control voltage. Indeed, the relationship is of sufficient linearity
that high fidelity AM modulation is possible using the SA5219. A
P-P
P-P
P-P
1997 Nov 07
4
Philips Semiconductors Product specification
SA5219Wideband variable gain amplifier
maximum control voltage frequency of about 20MHz permits video
baseband sources for AM.
A stabilized bandgap reference voltage is made available on the
SA5219 (Pin 7). For fixed gain applications this voltage can be
resistor divided, and then fed to the gain control terminal (Pin 8).
Using the bandgap voltage reference for gain control produces very
stable gain characteristics over wide temperature ranges. The gain
setting resistors are not part of the RF signal path, and thus stray
capacitance here is not important.
The wide bandwidth and excellent gain control linearity make the
SA5219 VGA ideally suited for the automatic gain control (AGC)
function in RF and IF processing in cellular radio base stations,
Direct Broadcast Satellite (DBS) decoders, cable TV systems, fiber
optic receivers for wideband data and video, and other radio
communication applications. A typical AGC configuration using the
SA5219 is shown in Figure 3. Three SA5219s are cascaded with
appropriate AC coupling capacitors. The output of the final stage
drives the full-wave rectifier composed of two UHF Schottky diodes
V
CC
R
1
Q
V
0–1V
AGC
Q
1
2
+
–
IN
Q
5
B
IN
A
I
1
Q
Q
3
4
Q
6
Figure 2. Equivalent Schematic of VGA
BAT17 as shown. The diodes are biased by R1 and R2 to V
CC
such
that a quiescent current of about 2mA in each leg is achieved. An
SA5230 low voltage op amp is used as an integrator which drives
the V
pin on all three SA5219s. R3 and C3 filter the high
AGC
frequency ripple from the full-wave rectified signal. A voltage
divider is used to generate the reference for the non-inverting input
of the op amp at about 1.7V . Keeping D3 the same type as D1 and
D2 will provide a first order compensation for the change in Schottky
voltage over the operating temperature range and improve the AGC
performance. R6 is a variable resistor for adjustments to the op
amp reference voltage. In low cost and large volume applications
this could be replaced with a fixed resistor, which would result in a
slight loss of the AGC dynamic range. Cascading three SA5219s
will give a dynamic range in excess of 60dB.
The SA5219 is a very user-friendly part and will not oscillate in most
applications. However, in an application such as with gains in
excess of 60dB and bandwidth beyond 100MHz, good PC board
layout with proper supply decoupling is strongly recommended.
R
R
2
3
A1
R
4
BANDGAP
REFERENCE
Q
7
Q
8
I
2
OUT
B
Ω
50
I
3
V
BG
50
Ω
SR00274
OUT
A
1997 Nov 07
RF/IF
INPUT
5219 5219
5219
R4
C4
–
5230
+
R6
Figure 3. AGC Configuration Using Cascaded SA5219s
5
V
CC
R1
R2
L1 L2
D1 D2
BAT 17
C3
R3
D3
R5
BAT 17
AGC
OUTPUT
V
CC
SR00275
Philips Semiconductors Product specification
SA5219Wideband variable gain amplifier
10µF
V
IN
50Ω
0.1µF
0.1µF
0.1µF
1
V
CC1
2
GND1
IN
3
A
4
GND1
IN
5
B
GND1
6
7
V
BG
V
8
AGC
V
CC2
GND
OUT
GND2
OUT
GND2
GND2
GND2
16
15
2
14
A
13
12
B
11
10
9
0.1µF
0.1µF
0.1µF
OUT
OUT
+
V
CC
V
5VDC
A
B
SR00276
Figure 4. VGA AC Evaluation Board
+5V
5219
50Ω
OUTPUT
50Ω
SOURCE
MINI CIRCUITS
2:1 BALUN
OR SIMILAR
50Ω
SOURCE
50Ω
SOURCE
1 : 2
+1V
V
AGC
50Ω
Figure 5. Broadband Noise Optimization
2:1 TURNS RATIO
LC TUNED
TRANSFORMER
+5V
5219
+1V
V
AGC
50Ω
Figure 6. Narrowband Noise Optimization
MINI CIRCUITS
4:1 BALUN OR
EQUIVALENT
1 : 4
+5V
5219
+1V
V
50Ω
AGC
Figure 7. Broadband Gain Optimization
50Ω
OUTPUT
50Ω
OUTPUT
This circuit will exhibit about a 7dB
noise figure with approximately
22dB gain.
This circuit will exhibit about a 7dB
noise figure with approximately
22dB gain. Narrowband circuits
have the advantage of greater stability, particularly when multiple devices are cascaded.
This circuit will exhibit about an 8dB
noise figure with 24dB gain.
SR00277
SR00278
SR00279
1997 Nov 07
6
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