A threshold voltage variation cancellation technique for analogue peripheral circuits of a display array using poly-Si TFTs

Polysilicon thin-film technology has become of great interest due to the demand for large area electronic devices. Display applications, memories and optical copier are among the fields where polysilicon thin-film transistors (poly-Si TFTs) are most commonly used. However the design of analogue blocks, by using Poly-Si TFTs, with constant specifications is very difficult because of the large variation of the threshold voltage of the poly-Si TFT across the wafer and the kink effect makes. In this paper we propose a circuit that can sense the voltage difference between two TFTs. This voltage can be used in order to design an improved current mirror with cancellation of threshold voltage variation