Linear Driver for PIN Diode
Attenuators
V 4.00
DR65-0002
Features
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SOW-16
Linearizes PIN Diode Attenuators Over a Wide
Attenuation Range
Output Currents up to 12 mA
Operates with a Single Supply Voltage of +3V to +12V
Low Quiescent Currents
Single Control Voltage
SOW-16, Wide Body Plastic Package
Test Boards are Available
Tape and Reel Packaging Available
Description
M/A-COM's DR65-0002 is a break point free driver that
produces a logarithmic output current suitable for
linearizing PIN diode based shunt attenuators. This driver,
in conjunction with customer defined external components,
produces a linear transfer function (dB/V) between the
input control voltage of the driver and the attenuation
output of the PIN attenuator. The DR65-0002 has been
optimized for linearizing M/A-COM鈥檚 AT10-0009 or
AT10-0017 attenuators, but will function well with most
types of cathode grounded, PIN attenuators. The driver is
packaged in a SOW-16 package for commercial SMT
applications. A typical schematic for a 30 dB, 7.5 dB/V
linear attenuator is shown in Figure 1.
Package outline conforms to JEDEC standard MS-013AA
Circuit Description:
(Reference Figures 1 and 2)
The input divider, R1 and the sum of R2 and R3, sets the
overall transfer function of the circuit. To increase the
transfer function, decrease the Control Voltage and the
value of R1. Varying the value of R4 will optimize the
linearity of the circuit. One can achieve a very linear
transfer function (<鹵 1 dB/V) by driving the attenuator over
a smaller portion of its dynamic range. In the case of the
AT10-0009 and AT10-0017 attenuators, this would be
limited to a dynamic range of 28 and 25 dB, respectively.
Temperature compensation is a function temperature
coefficient of the thermistor, R3, and the ratio of R2 to R3,
and can only be optimized once the transfer function and
linearity component values have been established.
Figure 1
RFin
+Vcc
C1
.01 碌F
R1
14
4
2
1,3,4
16,14,13
Vcontrol
(0 to 4V)
39K
IN
12
7
ATTENNUATOR
DR65-0002
R2
680
REF
3
5
5,6,8
9,11,12
R3
(PTCT)
330
R4
360
10
RFoutput
NOTES:
TRANSFER FUNCTION IS 7.5 dB/V
Vcontrol IS 0V to 4.0V
+Vcc IS 5.0V 鹵 5%
R3 IS A POSITIVE TEMPERATURE COEFFICIENT THERMISTOR
ATTENUATOR IS AT10-0009 OR AT10-0017
SCHEMATIC
LINEAR ATTENUATOR
1
2
