AD8276/AD8277

Rev. A | Page 16 of 20

APPLICATIONS INFORMATION

CONFIGURATIONS

The AD8276/AD8277 can be configured in several ways (see

Figure 42 to Figure 46). All of these configurations have excellent

gain accuracy and gain drift because they rely on the internal

matched resistors. Note that Figure 43 shows the AD8276/AD8277

as difference amplifiers with a midsupply reference voltage at

the noninverting input. This allows the AD8276/AD8277 to be

used as a level shifter, which is appropriate in single-supply

applications that are referenced to midsupply.

As with the other inputs, the reference must be driven with a

low impedance source to maintain the internal resistor ratio. An

example using the low power, low noise OP1177 as a reference

is shown in Figure 41.

INCORRECT

V

CORRECT

AD8276

OP1177

+

–

V

REF

AD8276

REF

Figure 41. Driving the Reference Pin

40kΩ

2

3

5

1

6

40kΩ

40kΩ

40kΩ

–IN

OUT

+IN

Figure 42. Difference Amplifier, Gain = 1

40kΩ

2

3

5

1

6

40kΩ

40kΩ

40kΩ

–IN

OUT

+IN

Figure 43. Difference Amplifier, Gain = 1, Referenced to Midsupply

40kΩ

2

3

5

1

6

40kΩ

40kΩ

40kΩ

IN

OUT

Figure 44. Inverting Amplifier, Gain = −1

40kΩ

5

1

2

3

6

40kΩ

40kΩ

40kΩ

OUT

IN

Figure 45. Noninverting Amplifier, Gain = 1

40kΩ

25

6

40kΩ

IN

OUT

3

1

40kΩ

40kΩ

Figure 46. Noninverting Amplifier, Gain = 2

DIFFERENTIAL OUTPUT

Certain systems require a differential signal for better perfor-

mance, such as the inputs to differential analog-to-digital

converters. Figure 47 shows how the AD8276/AD8277 can

be used to convert a single-ended output from an AD8226

instrumentation amplifier into a differential signal. The internal

matched resistors of the AD8276 at the inverting input maximize

gain accuracy while generating a differential signal. The resistors at

the noninverting input can be used as a divider to set and track

the common-mode voltage accurately to midsupply, especially

when running on a single supply or in an environment where

the supply fluctuates. The resistors at the noninverting input

can also be shorted and set to any appropriate bias voltage. Note

the AD8276 because it is not pinned out.

AD8276

AD8226

+IN

–IN

R

R

R

R

–OUT

+OUT

Figure 47. Differential Output With Supply Tracking on Common-Mode

Voltage Reference