adg781 Analog Devices, Inc., adg781 Datasheet - Page 6

• Manufacturer Part Number: adg781
• Description: 2.5
  Quad Spst Switches In Chip Scale Package
• Manufacturer: Analog Devices, Inc.

ADG781/ADG782/ADG783
APPLICATIONS
Figure 1 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.
–100
–110
–120
–130
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–30
–40
–50
–60
–70
–80
–90
10k
10k
100k
100k
FREQUENCY – Hz
FREQUENCY – Hz
1M
1M
V
DD
V
DD
= 5V, 3V
= 5V, 3V
10M
10M
100M
100M
(MSB) IN4
D1
(LSB) IN1
IN2
IN3
–10
2.5V
–2
–4
–6
25
20
15
10
–5
0
5
0
10k
0
V
T
0.5
DD
A
C1
S1
S2
S3
S4
= 25 C
= 5V
33k
R1
100k
V
1
DD
GND
5V
= 3V
1.5
SOURCE VOLTAGE – V
D1
D2
D3
D4
FREQUENCY – Hz
GAIN RANGE 2 TO 16
2
1M
240k
120k
2.5
R4
R6
120k
120k
120k
R10
R8
R9
3
240k
120k
10M
R5
R7
5V
3.5
AD820
V
DD
4
= 5V
100M
R2
510k
R3
510k
4.5
2.5V
V
5
OUT