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

摘要

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 mu m standard CMOS process, the circuit consumes 39 x 17.5 mu m(2) of silicon area. Post-layout simulation results indicate that the hysteresis width of the Schmitt trigger can be adjusted from 170 to 270mV and the ratio of the hysteresis width variation to supply voltage is 11.11%. Operated with 0.8V supply voltage, the power consumption of the circuit ranges from 0.48 to 1.12mW.