A Low Noise Thermoelectric Infrared Detector Microsystem in a Digital CMOS Technology

A low noise sensor interface for low-frequency thermoelectric infrared sensor applications is described which uses chopper technique to reduce low-frequency noise and offset. The circuit has been integrated in a transistor-only 1 ¿m single-poly, n-well CMOS process. It features a gain of 52 dB with a 500 Hz bandwidth and a CMRR of more than 70 dB. The equivalent input noise is 15 nV/¿Hz and free from 1/f-noise. The input offset is 1.5 ¿V for a tuning error of less than 4 %. The resulting sensor system allows the detection of a minimum required radiation signal of below 120 nW/mm². The amplifier consumes 1.3 mW.