Switched-capacitor circuits using polysilicon on quartz thin-film technology

It is shown that switched capacitor amplifiers and digital-to-analog converters can be built with adequate speed, voltage swing, and precision for AMLCDs (active-matrix liquid crystal displays) and other large-area electronic applications. Fully integrated polysilicon TFT (thin-film transistor) analog switched-capacitor circuits offer an alternative approach to data driver design. Switched capacitor circuits built entirely using polysilicon thin-film devices on quartz substrates has been demonstrated. Charge redistribution amplifiers and digital-to-analog converters are shown to operate at clock rates above 50 kHz, despite the relatively poor performance of polysilicon TFTs in comparison to conventional MOSFETs. Better than 8 b DAC accuracy is demonstrated. These results offer the possibility of greatly increased functionality on large-area devices such as flat-panel displays, page-width scan arrays, or page-width print heads.<>