Low gain-error instrumentation amplifier for current sensing

This paper presents the design of a low gain-error pseudo rail-to-rail indirect current feedback instrumentation amplifier (In-Amp). In order to reduce the gain error introduced by the input common mode voltage variations, MOS transconductors regulated by specially designed folded-cascoded amplifier are used. Simulated gain error is only about 0.2% with input common mode voltage ranging from half VDD to VDD.