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Why is two op-amp instrumentation amp not recommended?
In Section 2.6 of "A Single-Supply Op-Amp Circuit Collection", it says "However, this topology is not recommended because the first op amp is operated at less than unity gain, so it may be unstable."
This configuration is also used in split-supply high-gain bioelectric amplifiers:
Amplifiers for bioelectric events: a design with a minimal
number of parts
They replace the tail-end resistor with an R and C in parallel to reduce the CMRR problem at high frequencies.
So why is it not recommended?
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