On‐chip power supply generation for self‐contained electronics using oxide thin‐film transistors

Abstract

SummaryThis paper presents a novel DC–DC converter suitable for low voltage operation using n‐type all enhancement amorphous indium–gallium–zinc oxide (a‐IGZO) thin‐film transistors (TFTs). This circuit employs the charge transfer switches (CTSs) which dynamically directs the charge flow in one direction. The limitations of conventional charge pump topology, that is, reverse charge sharing phenomenon and limited output voltage, are mitigated in the proposed design. It offers a voltage conversion efficiency (VCE) of 97.8% and maximum power efficiency of 91.1% at a load current of 5 μA when simulated using an in‐house analytical model in cadence virtuoso environment. It is capable of working at a voltage as low as 3 V provided by thin‐film, printed batteries. To the best of author's knowledge, this is the first design, which demonstrates on‐chip power supply generation for oxide TFT‐based circuits using a single thin‐film battery (equivalent voltage) which offers the highest output DC voltage of 14.36 V at a clock frequency and input voltage of 1 MHZ and 3 V, respectively. Further, an on‐chip clock generator is implemented to generate all signals required by the charge pump circuit. The proposed circuit provides highest VCE and power efficiency in comparison to reported circuits using same technology. Hence, it finds potential application in next era self‐contained electronics, such as smart packaging and wearable devices using flexible electronics.