OP77

Rev. E | Page 11 of 16

APPLICATIONS

OP77E

R2

1M

Ω

R4

1M

Ω

+15V

–15V

R1

1k

Ω

R3

1k

Ω

7

6

4

2

3

0.1µF

0.1µF

Figure 27. Precision High-Gain Differential Amplifier

OP77 make it possible to obtain performance not previously

available in single-stage, very high-gain amplifier applications.

For best CMR,

2

R

1

R

must equal

4

R

3

R

. In this example, with a

10 mV differential signal, the maximum errors are as listed in

Table 7.

Table 7. Maximum Errors

Type

Amount

Common-Mode Voltage

0.01%/V

Gain Linearity, Worst Case

0.02%

0.003%/°C

0.008%/°C

+15V

–15V

100

Ω

7

6

4

2

3

0.1µF

0.1µF

10µF

OUTPUT

INPUT

OP77

Figure 28. Isolating Large Capacitive Loads

This circuit reduces maximum slew rate but allows driving

capacitive loads of any size without instability. Because the boon

resistor is inside the feedback loop, its effect on output

impedance is reduced to insignificance by the high open-loop

gain of the OP77.

R1

100k

Ω

R3

1k

Ω

R4

990

Ω

R5

10

Ω

6

2

3

R2

100k

Ω

OP77

Figure 29. Basic Current Source

R1

R3

+15V

–15V

R4

R5

6

2N2222

2N2907

2

3

R2

OP77

(

)

GIVEN R3 = R4 + R5, R1 = R2

R3

R1 – R5

Figure 30. 100 mA Current Source

These current sources can supply both positive and negative

current into a grounded load.

Note that

1

R

3

R

2

R

4

R

5

R

2

R

4

R

5

R

Z

O

+

⎟

⎠

⎞

⎜

⎝

⎛

+

=

1

2

R

4

R

5

R +

must =

1

R

3

R