A-IGZO TFT based operational amplifier and comparator circuits for the adaptive DC-DC converter

Abstract

In this paper, we present an operational amplifier (op-amp) based on amorphous Indium-Gallium-Zinc-Oxide thin-film transistors (a-InGaZnO TFTs) to achieve a comparator operated by pulse-width-modulation (PWM) control-loop structure, which can be used for dc-dc converter circuits integrated in the display driving system. Based on electrical characteristics of the fabricated a-InGaZnO TFT, we proposed a novel NMOS op-amp to achieve the overall gain of 19.2dB. On the basis of the proposed op-amp, we fabricated a-InGaZnO TFT comparator circuit, which could successfully operate at 100 Hz to control the duty ratio from 25% to 75% with the slew rate of 0.625V/μs. © 2014 Society for Information Display.