RF COMMUNICATIONS PRODUCTS
SA602A
Double-balanced mixer and oscillator
Product specification
Replaces datasheet of April 17, 1990
IC17 Data Handbook
1997 Nov 07
Philips Semiconductors
Philips Semiconductors
Product specification
Double-balanced mixer and oscillator
SA602A
DESCRIPTION
The SA602A is a low-power VHF monolithic double-balanced mixer
with input amplifier, on-board oscillator, and voltage regulator. It is
intended for high performance, low power communication systems.
The guaranteed parameters of the SA602A make this device
particularly well suited for cellular radio applications. The mixer is a
“Gilbert cell” multiplier configuration which typically provides 18dB of
gain at 45MHz. The oscillator will operate to 200MHz. It can be
configured as a crystal oscillator, a tuned tank oscillator, or a buffer
for an external LO. For higher frequencies the LO input may be
externally driven. The noise figure at 45MHz is typically less than
5dB. The gain, intercept performance, low-power and noise
characteristics make the SA602A a superior choice for
high-performance battery operated equipment. It is available in an
8-lead dual in-line plastic package and an 8-lead SO (surface-mount
miniature package).
PIN CONFIGURATION
D and N Packages
1
2
3
4
8
7
6
5
IN
A
IN
B
GND
OUT
A
V
CC
OSC
E
OSC
B
OUT
B
SR00068
Figure 1. Pin Configuration
APPLICATIONS
FEATURES
•
Low current consumption: 2.4mA typical
•
Excellent noise figure: <4.7dB typical at 45MHz
•
High operating frequency
•
Excellent gain, intercept and sensitivity
•
Low external parts count; suitable for crystal/ceramic filters
•
SA602A meets cellular radio specifications
ORDERING INFORMATION
DESCRIPTION
8-Pin Plastic Dual In-Line Plastic (DIP)
8-Pin Plastic Small Outline (SO) package (Surface-mount)
•
Cellular radio mixer/oscillator
•
Portable radio
•
VHF transceivers
•
RF data links
•
HF/VHF frequency conversion
•
Instrumentation frequency conversion
•
Broadband LANs
TEMPERATURE RANGE
-40 to +85°C
-40 to +85°C
ORDER CODE
SA602AN
SA602AD
DWG #
SOT97-1
SOT96-1
ABSOLUTE MAXIMUM RATINGS
SYMBOL
V
CC
T
STG
T
A
θ
JA
Maximum operating voltage
Storage temperature range
Operating ambient temperature range SA602A
Thermal impedance
D package
N package
PARAMETER
RATING
9
-65 to +150
-40 to +85
90
75
UNITS
V
°C
°C
°C/W
°C/W
1997 Nov 07
2
853-1424 18662
Philips Semiconductors
Product specification
Double-balanced mixer and oscillator
SA602A
BLOCK DIAGRAM
8
V CC
VOLTAGE
REGULATOR
7
6
5
OSCILLATOR
GROUND
1
2
3
4
SR00069
Figure 2. Block Diagram
AC/DC ELECTRICAL CHARACTERISTICS
V
CC
= +6V, T
A
= 25
°
C; unless otherwise stated.
LIMITS
SYMBOL
V
CC
f
IN
f
OSC
PARAMETER
Power supply voltage range
DC current drain
Input signal frequency
Oscillator frequency
Noise figure at 45MHz
Third-order intercept point
Conversion gain at 45MHz
R
IN
C
IN
RF input resistance
RF input capacitance
Mixer output resistance
(Pin 4 or 5)
RF
IN
= -45dBm: f
1
= 45.0MHz
f
2
= 45.06MHz
14
1.5
3
1.5
3.5
TEST CONDITIONS
MIN
4.5
2.4
500
200
5.0
-13
17
5.5
-15
SA602A
TYP
MAX
8.0
2.8
V
mA
MHz
MHz
dB
dBm
dB
kΩ
pF
kΩ
UNITS
DESCRIPTION OF OPERATION
The SA602A is a Gilbert cell, an oscillator/buffer, and a temperature
compensated bias network as shown in the equivalent circuit. The
Gilbert cell is a differential amplifier (Pins 1 and 2) which drives a
balanced switching cell. The differential input stage provides gain
and determines the noise figure and signal handling performance of
the system.
The SA602A is designed for optimum low power performance.
When used with the SA604 as a 45MHz cellular radio second IF and
demodulator, the SA602A is capable of receiving -119dBm signals
with a 12dB S/N ratio. Third-order intercept is typically -13dBm (that
is approximately +5dBm output intercept because of the RF gain).
The system designer must be cognizant of this large signal
limitation. When designing LANs or other closed systems where
transmission levels are high, and small-signal or signal-to-noise
issues are not critical, the input to the SA602A should be
appropriately scaled.
Besides excellent low power performance well into VHF, the
SA602A is designed to be flexible. The input, RF mixer output and
oscillator ports can support a variety of configurations provided the
designer understands certain constraints, which will be explained
here.
The RF inputs (Pins 1 and 2) are biased internally. They are
symmetrical. The equivalent AC input impedance is approximately
1.5k || 3pF through 50MHz. Pins 1 and 2 can be used
interchangeably, but they should not be DC biased externally.
Figure 5 shows three typical input configurations.
The mixer outputs (Pins 4 and 5) are also internally biased. Each
output is connected to the internal positive supply by a 1.5kΩ
resistor. This permits direct output termination yet allows for
balanced output as well. Figure 6 shows three single ended output
configurations and a balanced output.
1997 Nov 07
3
Philips Semiconductors
Product specification
Double-balanced mixer and oscillator
SA602A
The oscillator is capable of sustaining oscillation beyond 200MHz in
crystal or tuned tank configurations. The upper limit of operation is
determined by tank “Q” and required drive levels. The higher the
“Q” of the tank or the smaller the required drive, the higher the
permissible oscillation frequency. If the required LO is beyond
oscillation limits, or the system calls for an external LO, the external
signal can be injected at Pin 6 through a DC blocking capacitor.
External LO should be at least 200mV
P-P
.
Figure 7 shows several proven oscillator circuits. Figure 7a is
appropriate for cellular radio. As shown, an overtone mode of
operation is utilized. Capacitor C3 and inductor L1 suppress
oscillation at the crystal fundamental frequency. In the fundamental
mode, the suppression network is omitted.
Figure 8 shows a Colpitts varactor tuned tank oscillator suitable for
synthesizer-controlled applications. It is important to buffer the
output of this circuit to assure that switching spikes from the first
counter or prescaler do not end up in the oscillator spectrum. The
dual-gate MOSFET provides optimum isolation with low current.
The FET offers good isolation, simplicity, and low current, while the
bipolar transistors provide the simple solution for non-critical
applications. The resistive divider in the emitter-follower circuit
should be chosen to provide the minimum input signal which will
assure correct system operation.
When operated above 100MHz, the oscillator may not start if the Q
of the tank is too low. A 22kΩ resistor from Pin 7 to ground will
increase the DC bias current of the oscillator transistor. This
improves the AC operating characteristic of the transistor and
should help the oscillator to start. A 22kΩ resistor will not upset the
other DC biasing internal to the device, but smaller resistance
values should be avoided.
0.5 to 1.3µH
22pF
5.5µH
V
CC
6.8µF
100nF
10nF
1nF
10pF
34.545MHz THIRD OVERTONE CRYSTAL
8
7
6
5
150pF
OUTPUT
602A
1.5 to
44.2µH
330pF
120pF
1
47pF
INPUT
220pF
100nF
0.209 to 0.283µH
2
3
4
SR00070
Figure 3. Test Configuration
1997 Nov 07
4
Philips Semiconductors
Product specification
Double-balanced mixer and oscillator
SA602A
8
V
CC
18k
6
7
25k
BUFFER
1.5k
4
1.5k
5
BIAS
BIAS
2
1
BIAS
1.5k
3
GND
1.5k
SR00071
Figure 4. Equivalent Circuit
602A
602A
602A
1
INPUT
2
1
2
1
2
a. Single-Ended Tuned Input
b. Balanced Input (For Attenuation
of Second-Order Products)
c. Single-Ended Untuned Input
SR00072
Figure 5. Input Configuration
1997 Nov 07
5
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