An integrated CMOS instrumentation amplifier with improved CMRR

Abstract

An instrumentation amplifier is described, which is based on the classical current-balancing technique that ensures this type of circuit achieves high immunity to common-mode signals. In the particular case of the circuit herein described, a CMRR of 110 dB was attained, thanks specially to improving the current mirror that balances the current between the input and the output stages of the amplifier. Prototypes of the circuit were fabricated in 0.6 /spl mu/m CMOS using MPW (multi-project wafer) services and were fully characterized.