A low-noise CMOS instrumentation amplifier for thermoelectric infrared detectors

A low-noise CMOS instrumentation amplifier for low-frequency thermoelectric infrared sensor applications is described which uses chopper technique to reduce low-frequency noise and offset, The offset reduction efficiency of the bandpass 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-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/root Hz. The typical residual input offset is 1.5 mu V. The amplifier power consumption is 1.3 mW.