A 140dB-CMRR current-feedback instrumentation amplifier employing ping-pong auto-zeroing and chopping

A current-feedback instrumentation amplifier (CFIA) is presented that uses ping-pong auto-zeroing and chopping to reduce offset, Mi noise, and output ripple. CFIAs are attractive because of their ability to sense differential input voltages in a common-mode voltage range (CMVR) that includes either of the supply rails. They can thus interface directly, for instance, with ground-referenced sensors in a single-supply system. This property results from the fact that the input voltage is sensed by an open-loop input stage, which typically exploits the inherent level-shift provided by the input transistors´ threshold voltage to sense beyond the rail.