OP497

Rev. E | Page 12 of 16

APPLICATIONS CIRCUIT

PRECISION ABSOLUTE VALUE AMPLIFIER

The circuit in Figure 36 is a precision absolute value amplifier

with an input impedance of 30 MΩ. The high gain and low

input signals. In this circuit, the input always appears as a common-

mode signal to the op amps. The CMR of the OP497 exceeds

120 dB, yielding an error of less than 2 ppm.

+15V

2

3

4

8

1

6

5

7

D1

1N4148

C1

30pF

D2

1N4148

1/4

OP497

1/4

OP497

–15V

R2

2k

Ω

C3

0.1µF

R3

1k

Ω

R1

1k

Ω

C2

0.1µF

Figure 36. Precision Absolute Value Amplifier

PRECISION CURRENT PUMP

Maximum output current of the precision current pump shown

in Figure 37 is ±10 mA. Voltage compliance is ±10 V with ±15 V

supplies. Output impedance of the current transmitter exceeds

3 MΩ with linearity better than 16 bits.

2

3

1

7

8

5

6

4

–15V

+15V

–

+

1/4

OP497

1/4

OP497

=

R5

100

Ω

10mA/V

R3

10k

Ω

R5

10k

Ω

R4

10k

Ω

R1

10k

Ω

R2

10k

Ω

±10mA

Figure 37. Precision Current Pump

PRECISION POSITIVE PEAK DETECTOR

polyethylene to minimize dielectric absorption and leakage.

current of the OP497.

2

3

1

7

8

5

6

4

+15V

1N4148

2N930

RESET

1/4

OP497

1/4

OP497

+

–15V

0.1µF

0.1µF

1k

Ω

1k

Ω

1k

Ω

1k

Ω

Figure 38. Precision Positive Peak Detector

SIMPLE BRIDGE CONDITIONING AMPLIFIER

Figure 39 shows a simple bridge conditioning amplifier using

the OP497. The transfer function is

R

R

R

R

R

V

V

F

REF

OUT

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

Δ

+

=

Δ

The REF43 provides an accurate and stable reference voltage for

be 0.1% or better with a low temperature coefficient.

2

3

1

7

8

5

6

4

+5V

REF43

6

2

4

+5V

R

R

R

2.5V

R +

ΔR

ΔR

R +

ΔRR

1/4

OP497

1/4

OP497

–5V

()

Figure 39. Simple Bridge Conditioning Amplifier Using the OP497