A fully/electronically controllable voltage-mode Schmitt trigger based on only single VDGA and its applications

Abstract

This article is objected to present a new fully/electronically controllable voltage-mode Schmitt trigger based on a modified voltage differencing gain amplifier (VDGA). It can offer both counterclockwise (CCW) and clockwise (CW) functions, without changing circuit topology. The proposed Schmitt trigger comprises merely one VDGA and three resistors. The hysteresis and amplitude of the output voltage of proposed Schmitt trigger can be independently controlled by corresponding bias currents of the VDGA. The modified VDGA was designed by a fully balanced differential transconductance technique based on 0.35 µm CMOS transistor technology, providing advantages in high gain, wide range of adjustability and symmetrical output signals. The performances of proposed Schmitt trigger were deeply investigated by not only simulation via PSpice program, but also experimental setup using commercially available integrated circuits. Both results agree well with the theoretical anticipation and are consistent each other. The total power consumption is approximately 1.39 mW at ± 1.5 V power supply. Additionally, to prove the practical use-abilities of the proposed Schmitt trigger, its applications in a voltage-mode relaxation oscillator, a triangular/square wave generator and a pulse width modulator are also included.