A CMOS readout circuit for pico-ampere thin film pyroelectric array detectors

Abstract

A 16-channel readout circuit able to process low frequency modulated (1-10 hertz) current signals in the pico-ampere range from a thin film pyroelectric array detector has been integrated in a 0.7 /spl mu/m CMOS technology. Each channel consists of a high gain (14 G/spl Omega/) transimpedance preamplifier having an input-referred current noise spectral density of 1.5 fA//spl radic/Hz at 10 Hz. A multiplier for demodulating the signal follows the preamplifier (chopper frequency fixed at 10 Hz). Finally, the signal is integrated over 8 periods before being converted by a 12-bit A/D converter. The multiplication, the integration and the A/D conversion are implemented within a single block using a first-order switched-capacitor incremental A/D converter architecture.