A Low-Voltage Bulk-Driven Differential CMOS Schmitt Trigger with Tunable Hysteresis

Abstract

This paper describes a low-voltage bulk-driven differential CMOS Schmitt trigger with tunable hysteresis for use in noise removal applications. The hysteresis of the proposed Schmitt trigger is designed based on a regenerative current feedback and its width is adjustable by two control voltages. The center of the hysteresis can also be adjusted by either the control voltages or input common-mode voltage. The principle operation of the proposed circuit is discussed, its main formulas are derived and its performance is verified by Cadence post-layout simulations. Designed in the TSMC 0.18[Formula: see text][Formula: see text]m standard CMOS process, the circuit consumes [Formula: see text]m2 of silicon area. Post-layout simulation results indicate that the hysteresis width of the Schmitt trigger can be adjusted from 170 to 270[Formula: see text]mV and the ratio of the hysteresis width variation to supply voltage is 11.11%. Operated with 0.8[Formula: see text]V supply voltage, the power consumption of the circuit ranges from 0.48 to 1.12[Formula: see text]mW.