Single/Dual/Triple/Quad

Operational Amplifiers

24

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Figure 9. Low Droop Rate Sample and Hold—S2 improves

accuracy and acquisition time by including the voltage drop

across S1 inside the feedback loop. R1 closes the feedback

ICL7622

A1

IH5141

ICL7622

A2

S/H

CONTROL

INPUT

100k

Ω

S1

S2

the time constant of this integrator is 100,000s. Since the input

far exceed the power-supply range.

-

+

1

µF

Figure 11. Pico Ammeter—The response time of this curcuit is

output and the inverting terminal of the amplifier.

Figure 12. 60Hz Twin “T“ Notch Filter—The low 1pA bias cur-

rent of the ICL7611 allows use of small 540pF and 270pF

capacitors, even with a notch frequency of 60Hz. The 60Hz

rejection is approximately 40dB.

+

-

CURRENT

SOURCE

Ω

+

-

OUTPUT

ICL7611

10M

Ω

10M

Ω

270pF

270pF

540pF

5M

Ω

LONG TIME CONSTANT INTEGRATOR

(Detailed Circuit Diagram — Figure 10)

-

+

Typical Operating Circuit