A Kind Of Lcd Driver Integral Type A / D Converter's Design

Many signals in nature world are analog, when we use digital signal processing technology to deal with them, first of all need to use A/D converter to convert analog signals to digital signals. As the development of electronic technology, A/D converters are changing towards the direction of high speed and high precision. We can use different methods to realize A/D converters. In order to achieve efficient, low-cost purpose, we need to choose appropriate A/D converters in different practical applications. Of all kinds of A/D converters, Integrating A/D Converter is used widely in low speed and high resolution meters because of high performance in anti-jamming, high resolution and low cost.This paper first analyzes several kinds of A/D converters, then introduces the principle of Dual-Slope A/D Converter. At last, by optimizing the performances of all modules, we get a converter which can operate well with 9V power supply. The maximal count is±19999 count and the accuracy is 0.005%. The circuit is composed of digital block and analog block. The analog block contains amplifier, comparator, integrator, bandgap voltage reference and so on. The digital block contains control logic, result counter and LCD drive.The successive integration technique was used to dispose overshoot results in resolution down, at the same time, offsets are cancelled using digital techniques instead. Savings in external parts cost are realized as well as improved noise performance and elimination of a source of electromagnetic and electrostatic pick-up. It can achieve 10μV resolution on a 200mV full scale range. The converter can directly drive LCD and has a reference; it requires only a few passive components to operate.The whole is based on standard 3μm CMOS process. The circuit has been simulated with Hsipce simulator in the Cadence design environment. The system simulation shows that all blocks can work well.