Inverters Using Only N-Type Indium Gallium Zinc Oxide Thin Film Transistors for Flat Panel Display Applications

Abstract

Two inverter architectures are proposed to be integrated on panels for flat panel display applications using only n-type amorphous indium gallium zinc oxide (IGZO) thin film transistors (TFTs). The proposed cross-coupled (CC) inverter uses the positive feedback effect of its CC structure to reduce the static current and increase the output voltage swing when using depletion mode n-type amorphous IGZO TFTs. The other proposed cross-coupled and bootstrapping (CCB) inverter also uses the cross-coupled structure and includes a capacitor for the bootstrapping effect to increase the operating frequency. The measured results show that the output voltage swing of the proposed CC inverter is from 0 to 14.50 V and that of the CCB inverter is from 0.15 to 14.57 V when VDD is 15 V at 20 kHz and the load capacitance is 103.0 pF. The power consumption of the CC and CCB inverters are 1.4 and 2.5mW, respectively, which are 29.3 and 53.4% of the power consumption of the ratioed inverter. (c) 2011 The Japan Society of Applied Physics