ADG711/ADG712/ADG713
APPLICATIONS INFORMATION
C1
Figure 20 illustrates a photodetector circuit with programmable
gain. An AD820 is used as the output operational amplifier.
With the resistor values shown in the circuit, and using different
combinations of the switches, gain in the range of 2 to 16 can be
achieved.
R1
33kΩ
+5V
AD820
D1
+2.5V
V
OUT
R2
510kΩ
+5V
R4
R5
240kΩ 240kΩ
S1
D1
D2
D3
D4
(LSB) IN1
IN2
R6
R7
R3
510kΩ
120kΩ 120kΩ
S2
S3
S4
R8
120kΩ
IN3
R9
120kΩ
+2.5V
(MSB) IN4
R10
120kΩ
GND
Figure 20. Photodetector Circuit with Programmable Gain
Rev. B | Page 12 of 16