A low-noise CMOS instrumentation amplifier for thermoelectric infrared detectors

Abstract

A low-noise CMOS instrumentation amplifier for low-frequency thermoelectric infrared sensor applications is described which uses a chopper technique to reduce low-frequency noise and offset. The offset reduction efficiency of the band-pass filter, implemented to reduce residual offset due to clock feedthrough, has been analyzed and experimentally verified. The circuit has been integrated in a transistor-only 1-/spl mu/m single-poly n-well CMOS process. It features a gain of 52 dB with a 500 Hz bandwidth and a common-mode rejection ratio (CMRR) of more than 70 dB. The equivalent input low frequency noise is 15 nV//spl radic/Hz. The typical residual input offset is 1.5 /spl mu/V. The amplifier power consumption is 1.3 mW.