Low noise multirate SC read-out circuitry for thermoelectric integrated infrared sensors

In this paper we present a switched capacitor multirate read-out circuit for thermoelectric infrared sensors integrated on chip. The target application is a passive intrusion detector. The signal generated by the sensor in this particular application is quite small (few tens of μV) and has a narrow bandwidth (0.1+10 Hz). It must be amplified (keeping the noise level as low as possible) and band pass filtered. An auto-zeroed low-noise transconductance stage transforms the sensor output voltage in a current, which is applied to a multirate switched capacitor integrator, performing the signal processing. A prototype was integrated in a 1.2 μm CMOS technology. Simulation and experimental results are reported