A Chopper Instrumentation Amplifier with Gain Error Reduction Loop

This chapter describes a stand-alone chopper current-feedback instrumentation amplifier (CFIA) that has improved performance compared to the one described in Chap. 4. It maintains the latter’s low noise and low offset, and also obtains high gain accuracy and low gain drift without trimming. This is achieved by applying dynamic element matching (DEM) to the input and feedback transconductors so as to average out their mismatch. To eliminate the resulting DEM ripple, a gain error reduction loop (GERL) is employed to continuously null the Gm mismatch. The concept and analysis of DEM and the GERL is presented in Sects. 5.2 and 5.3. Then the similarities and differences between the offset reduction loop (ORL) and the GERL are discussed, together with their effects on the input and feedback Gm transfer functions.