Differential Amplifier Using Polysilicon TFTs Processed at Low Temperature to be Integrated with TFT Hall Sensor

This paper presents the design steps of a micro system entirely carried out on glass substrate. The polycrystalline silicon thin film technology developed in our laboratory is already used to fabricate different kinds of sensors and digital devices. The main goal of this study is to be able to validate the use of polycrystalline silicon thin film transistors (poly-Si TFT) to design analog circuits. The development of CTFT (complementary thin film transistor) using N-type and P-type TFTs has already been used to design digital circuits. The main advantage of this technology is the possibility to fabricate electronic devices at low temperature with good electrical characteristics. Several steps are necessary for the realization of such devices. The most important is the modelling and the simulation of poly-Si TFTs in dynamic mode. This phase can be carried out by fabricating poly-Si TFTs and by characterizing them. The fabrication of a TFT based position sensor allows validating the behaviour model of poly-Si TFTs and the polysilicon thin film technology as a good challenger for the designing of different kinds of devices. All the devices presented in this paper are entirely carried out in the cleanroom in the laboratory