Optical Sensor Circuit
Original Publication Date: 1980-Dec-01
Included in the Prior Art Database: 2005-Feb-12
This circuit is for detecting low amplitude optical signals through a differential amplifier, and filtering out higher amplitude noise through a feedback circuit which includes a comparator and a capacitor. The capacitor is charged by a constant current source and connected to the differential amplifier in order to filter out low frequency noise, while the comparator forces a constant output voltage from the differential amplifier unless the desired pulse signal or high frequency noise signals are present on the input. A second comparator filters low amplitude, high frequency noise, while a pulse width discriminator filters high frequency noise of a pulse width shorter than the desired signal.