Adjustable hysteresis CMOS Schmitt triggers

Abstract

Adjustable hysteresis CMOS Schmitt trigger design strategies are investigated and two new inverter based designs are proposed. The sizing of the two feedback inverters controls the two trip points of the structure independently. By the addition of voltage controlled current sinking and/or sourcing transistors, the hysteresis window can be easily moved without changing its width. Moreover the new designs are immune to the kick-back noise coming from the succeeding blocks.