Phone Displays The Research And Design Of Cmos Window Comparator Oscillator

The work in this paper is part of the project named Research on TFT-LCD Display Driver IC for Colored Display Cellular Phone, which is carried out by Northwestern Polytechnical University- Aviation Microelectronics Center.After the displaying principle and driving scheme of TFT-LCD are introduced, the driver IC is divided into seven parts, such as Logic Circuit and Digital Interface, Source Driver, Gate Driver, GRAM, Built-in Power Supply Circuit, Gamma Correction Circuit and OSC. As an emphasis, a high quality built-in CMOS oscillator in TFT-LCD driver IC used for mobile phone is studied and designed in this paper. The oscillator is based on window-comparator principle. A couple of comparators with high sensitivity are used as the key element of the switch control circuit, and constant current sources are used for charging and discharging the capacitor. Then the oscillator circuit, which is with low power supply voltage, high frequency and high precision, is actualized through the designing flow of analog integrate circuit. Finally, the HSPICE simulation results with 0.25um CMOS process of the circuit are given. It is shown that the frequency is influenced little by processes. The error is less than ±5%.Besides, an operational amplifier, a comparator and a reference voltage source, which are modules of the OSC, are learned and designed.