Datasheet

ADG711/ADG712/ADG713
Rev. B | Page 12 of 16
APPLICATIONS INFORMATION
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.
0
0042-022
R4
240kΩ
S1
S2
S3
S4
D1
D2
D3
D4
(LSB) IN1
IN2
IN3
(MSB) IN4
+2.5V
+5V
AD820
R1
33kΩ
D1
C1
R5
240kΩ
R6
120kΩ
R8
120kΩ
R9
120kΩ
R10
120kΩ
GND
+5V
R7
120kΩ
R3
510kΩ
R2
510kΩ
V
OUT
+2.5V
Figure 20. Photodetector Circuit with Programmable Gain