Analog Circuits Cookbook, 2nd Edition

3 Measurements (audio and video)

Four opamp inputs are better than two

Ingenious video opamp

In an instrumentation amplifier, both inputs are high impedance and floating with respect to ground, but performance is limited to the sub-rf range. The opamp described here avoids that limitation, operating up to many tens of MHz.

The INGENIous enginEER (in continental Europe the word for engineer is ingenieur) is always looking for elegant and economical solutions to design problems. Back in the 1970s when the RCA CA3130 BiMOS opamp became available, it was clearly the answer to many an engineer’s prayer, with its very high input impedance compared with the existing bipolar types.

I decided it was just the thing for the detector in a bridge circuit, but ...