A 1.25-V Power Source Based on Solid-State Battery and Low Dropout Regulator Integrated With E-Mode a-IGZO and D-Mode ITO Thin-Film Transistors

In this article, we present a power source comprising externally linked solid-state thin-film lithium-ion battery (LIB) and thin-film transistors (TFTs)-based low-dropout (LDO) regulator circuit. The LIB utilizes amorphous InGaZnO (a-IGZO) as the anode material for the prospect of integration. It maintains excellent performance even after cycling and rate measurements at a current rate of 4.0 C. The LDO circuit employs integrated a-IGZO enhancement-mode and InSnO (ITO) depletion-mode (D-mode) TFTs as an alternative to CMOS technology for their outstanding mobility and process compatibility. The resistors are meticulously designed for a low temperature coefficient (TC) of the voltage reference. The LDO delivers an output voltage of 1.25 V and a low quiescent current of only 1.6~\mu A. Its exceptional line regulation of 0.66%/V and load regulation of 180~\mu V/ \mu A stem from the high voltage gain of the error amplifier with D-mode loads. The proposed power source demonstrates a stable output voltage of 1.25 V after charging and shows minimal variation during a 100-s measurement period. This addresses the issue in thin-film LIBs, where voltage decreases with battery capacity consumption.