Research And Design Of An LCD Bias Voltage Control System

Liquid crystal display (LCD) opened a new era of display device since its birthat the seventies of the last century. Because of its low power consumption, lowdriving voltage, showing a large amount of information, high reliability, low cost, noradiation, no pollution, easy to carry and so on, after40years of development, nowwidely used in electronic watches, calculators, indoor phone, MP4, mobile phones,digital cameras, GPS, liquid crystal displays, etc., has become a necessity in our dailylives.This thesis on the basis of the background information which introduces thedevelopment of today’s LCD industry, LCD structure and display principle,characteristics, discusses a kind of LCD bias voltage control system, including circuitdesign, functional simulation, digital modelling, layout design, and so on. The circuitdesign from the gate-level unit describes the circuit has a bias selection function,VLCD adjustable internally function, the bias resistor selection function. Functionalsimulation verifies circuit design each function, power consumption and otherparameters. In the circuit’s layout design mainly completed the overall layout of thewiring, achieving the matching of the resistors and capacitors, and using the CadenceCalibre layout verification tools for the DRC and LVS check.A highlight of this thesis is the digital modelling for the LCD bias voltage.Under normal circumstances, in order to LCD bias voltage bring into the chip as awhole simulation, using the Verilog-A modelling methods. This method is morecumbersome for the designers who don’t understand the Verilog-A language. On thebasis of the principle which I am familiar with the LCD, and combining the practicalexperience, the bias voltage according to the display principle can be indicatedrespectively by ‘0’ and ‘1’. After this method to the bias voltage for digital modelling,bias voltage which has the analog nature can be directly placed into the overall chipdigital simulation. This modelling approach is also very conducive to graphicsdecoding in the latter part of digital simulation, and after several projects proved thatthis method is simple and effective. In addition, the LCD bias voltage control system because it can be set differentbias, a variety of driving voltage, different bias resistor, either directly or after asimple modification can be brought into the other LCD bias voltage circuit which hasthe different bias, different kinds of waveforms. It has a very wide range ofapplications.