Energy-Efficient Full-Swing Logic Circuits With Unipolar TFTs on Flexible Substrates

Thin-film transistor (TFT) technologies often have only n-type conductivity, and therefore, the realization of CMOS-like logic gates becomes a challenge. Conventional approaches to realize logic gates in such technologies result in limited swing and excessive direct-path current. In this article, we propose logic gates that mitigate these problems. As a proof of concept, a three-to-eight decoder and a column of pixel circuits with n-type only a-Si:H TFTs have been fabricated on flexible plastic substrates. Simulation and measurement results demonstrate that the decoder maintains unity stage-to-stage gain, while its static leakage current is reduced by 85% compared with the conventional implementation. The layout area is reduced by 20% compared with prior implementations. In addition, the circuit performance under applied mechanical strain was also consistent with the theory.