Realization of Low-Power Digital Circuits With Unipolar TFTs on Flexible Substrate

Abstract

There is growing interest in low-cost, low-thermal-budget electronics, particularly for displays, flexible body sensors, and affordable IoT devices. The potential of thin-film transistors (TFTs) in enabling these large-area, low-cost electronics has been proven. However, implementing complex circuits and on-chip SRAM with TFTs, which often lack complementary transistor types, poses challenges due to limited output swing, and excessive direct path current that leads to high power consumption. This paper introduces digital circuit designs that address these challenges. As a proof of concept, several key building blocks such as primary logic gates, decoders, and SRAM cells were fabricated using only n-type amorphous silicon (a-Si:H) TFTs on a glass and flexible substrate, and the impact of bending on circuit robustness was examined. The measurement results indicate that the proposed 2-to-4 decoder circuit maintains full output swing and reduces total average power consumption by 20.8compared to the state-of-the-art bootstrap circuit. Furthermore, the proposed SRAM cell reduces static power consumption by approximately 56× compared to a conventional 6T SRAM cell with unipolar TFTs.