SIGNAL PROCESSOR FOR PYROELECTRIC INFRARED SENSOR

摘要

A signal processor which only amplifies AC signals included in input signals (Vin) inputted from a pyroelectric infrared sensor (1) at a prescribed amplification factor. The processor is constituted of a low-pass filter circuit (11) which only outputs the DC component included in the input signals (Vin) from the sensor (1) and a differential amplifier circuit (21) which only amplifies and outputs AC components included in the input signal (Vin) based on the DC signal (VDC) outputted from the filter circuit (11) and the input signals (Vin) from the sensor (1). To the amplifier circuit (21), the input signals (Vin) from the sensor (1) and the DC signal (VDC) which are generated by passing the signals (Vin) through the filter circuit (11) are inputted. The differential amplifier circuit (21) generates an output voltage (Vout) by only amplifying the AC signals (VAC) at an amplification factor which is determined from the relation with a resistance by amplifying (Vin-VDC). <IMAGE>