AD623

Rev. D | Page 16 of 24

APPLICATIONS INFORMATION

BASIC CONNECTION

Figure 42 and Figure 43 show the basic connection circuits for

supplies should be capacitively decoupled close to the power pins of

the device. For the best results, use surface-mount 0.1 μF ceramic

chip capacitors and 10 μF electrolytic tantalum capacitors.

OUTPUT

REF

REF (INPUT)

+2.5V TO +6V

10µF

0.1µF

–2.5V TO –6V

10µF

0.1µF

Figure 42. Dual-Supply Basic Connection

OUTPUT

REF

REF (INPUT)

+3V TO +12V

10µF

0.1µF

Figure 43. Single-Supply Basic Connection

The input voltage, which can be either single-ended (tie either

−IN or +IN to ground), or differential is amplified by the

programmed gain. The output signal appears as the voltage

difference between the OUTPUT pin and the externally applied

voltage on the REF input. For a ground-referenced output, REF

should be grounded.

GAIN SELECTION

precisely, by whatever impedance appears between Pin 1 and

Pin 8. The AD623 is designed to offer accurate gains using 0.1%

to 1% tolerance resistors. Table 5 shows the required values of

calculated by

= 100 kΩ/(G − 1)

REFERENCE TERMINAL

The reference terminal potential defines the zero output voltage

and is especially useful when the load does not share a precise

ground with the rest of the system. It provides a direct means of

injecting a precise offset to the output. The reference terminal is

also useful when bipolar signals are being amplified because it

can be used to provide a virtual ground voltage. The voltage on

Table 5. Required Values of Gain Resistors

Desired Gain

Calculated Gain Using 1% Resistors

2

100 k

2

5

24.9 k

5.02

10

11 k

10.09

20

5.23 k

20.12

33

3.09 k

33.36

40

2.55 k

40.21

50

2.05 k

49.78

65

1.58 k

64.29

100

1.02 k

99.04

200

499

201.4

500

200

501

1000

100

1001