Dual hysteresis signal detection circuit

摘要

A dual hysteresis signal detection circuit is proposed for detecting a duration of a signal with two hysteresis comparators. There is a first band pass filter for inputting the signal and outputting the signal having a first frequency. A first hysteresis comparator electrically couples to the first band pass filter for comparing with the first frequency of the signal to output a first square wave signal according a first high voltage and a first low voltage. A second hysteresis comparator electrically couples to the first band pass filter for comparing with the first frequency of the signal to output a second square wave signal according to a second high voltage and a second low voltage. A first detection circuit electrically couples to the first hysteresis comparator for detecting a part of the signal having the first frequency that is higher than the first high voltage and lower than the first low voltage to output a first detection signal according to the first square wave signal. A second detection circuit electrically couples to the second hysteresis comparator for detecting a part of the signal having the first frequency that is higher than the second high voltage and lower than the second low voltage to output a second detection signal according to the second square wave signal. The duration of the signal being detected according to the first detection signal and the second detection signal. <IMAGE>