X100_instrumentation_amplifier

Published:2009/7/24 3:08:00 Author:Jessie | From:SeekIC

This circuit requires two 1.5-V cells connected directly (no power switch) to the V+ and V- terminals. Total current drain is 2.8 μA. R11 matches gains of Al and A2 to get maximum common-mode rejection ratio. Figure 8-32B shows both CMRR and voltage gain across frequency range. C1 balances wiring (rather than amplifier frequency response) to give an additional 10 to 20 dB of CMRR. Maximum peak-to-peak output into a 100-kΩ load is about 1.8 V. When doing power measurements on this circuit, remember that even a 1-MΩ scope probe placed between +1.5 V and -1.5 V more than doubles the power drawn from the batteries.



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