Analysis and design of a-Si:H TFTs based charge pump circuit with only capacitive load

Abstract

This paper deals with the suggestion of a charge pump based on hydrogenated amorphous silicon thin-film transistors with purely capacitive load. Based on a Dickson charge pump configuration, the proposed circuit uses diode- connected amorphous silicon transistors as switches and amorphous silicon transistors connected as capacitors for pumping capacitors. Using thin-film transistors as capacitors may be a significant factor in minimizing the circuit area and thus the start-up time. Design considerations of charge pump key parameters are presented. Investigations include output voltage, clock frequency, transistors sizing, rise time and ripple voltage. Results show that with significant optimization, the proposed circuit can be used to deliver high gate drive voltages for amorphous silicon drivers.