PULSE GENERATOR

摘要

PROBLEM TO BE SOLVED: To solve the problem of a conventional pulse generator for comparing an analog input voltage with a threshold value to generate a logic pulse that causes an increased consumed current in the case of producing the threshold value through resistance division and using a transistor differential pair for voltage comparison. SOLUTION: An inverter having inversion threshold values different between rising and falling of an input voltage Vin is configured by intermitting operations of transistors QP3, QN3 in response to an output level. The gate length of a transistor QP2 is designed shorter than that of the transistor QP1, then the transistor QP2 is turned off after the transistor QP1 is turned off in the case of the rising of the input voltage Vin. As a result, the inversion threshold value Vth-H of the inverter at the rising is decided by a combination of the transistors QP2, QN1, and when the input voltage Vin reaches the inversion threshold value Vth-H, the output of the inverter changes from level H to level L. Similarly, the transistor QN2 is turned off after the transistor QN1 is turned off in the case of the falling of the Vin, and an inversion threshold value Vth-L of the inverter in the falling state is decided by a combination of the transistors QP1, QN2, and a relation of the Vth-L