Design Of Low Power Consumption And High Performance LCD Driver Circuit

In recent years,with the rapid rise of electronic communication technology,people will use a variety of display equipment.Among them,Liquid Crystal Display(LCD)has the unique advantages of small size,low power consumption and high Display quality.It is widely used in various low-power electronic products and becomes the mainstream of the whole Display technology.The LCD drive circuit is bound to develop towards low power consumption and high performance.Based on the research and analysis of LCD display principle and drive technology,this paper proposes a kind of LCD drive circuit with low power consumption,high performance and high integration,and designs and simulates the reference source circuit,oscillator circuit,charge pump(CP)booster circuit,bias circuit,LCD drive outlet and GPIO(General purpose input/output)multiplexing circuit.In view of the capacitive characteristics of the LCD screen,the traditional bias circuit is improved,and a kind of weak tube bias circuit with operational amplifier is designed.This kind of bias circuit can reduce the driving output voltage affected by the LCD,which can not only improve the display performance,but also greatly reduce the power consumption.To solve the problem that the power supply voltage reduction affects the display clarity,the Charge Pump booster module is integrated in the circuit.When the power supply voltage is less than the LCD display voltage,the drive output voltage can be boosted to the required display voltage.Compared with the traditional method of increasing the capacitor off-chip,the integration degree is higher.At the same time,a stabilized voltage modulation system is added to improve the efficiency of the charge pump,reduce the ripple of the output voltage of the charge pump,so as to improve the LCD display quality.In addition,aiming at the problem that the high level of GPIO output of most MCU in the market cannot exceed the power supply voltage,and cannot be reused with LCD driver outlet with boost,this paper designs a kind of LCD driver outlet and GPIO multiplexing circuit.When the multiplexing circuit selects the port as the output port of the LCD driver,the output level of the LCD driver can be higher than the power supply voltage.When a multiplexing circuit selects a port as GPIO,it correctly outputs the high and low levels of GPIO.This makes IO ports more powerful,chips more widely used,and greatly reduces the area of the chip.In this paper,the LCD driver circuit was designed based on the 0.18 m CMOS process,and the circuit was simulated with SPECTRE of CADENCE platform.Finally,the chip layout was given and the chip was tested.The LCD drive circuit can drive 4 row 20 row dot matrix LCD,and realize the multiplexing of 24 channel boost LCD drive outlet and GPIO port.When the chip supply voltage is 3V,the LCD drive current is less than 10uA.When the power supply voltage is 2.5V,the LCD drive output can be boosted to about 3V.The designed LCD driver chip has been taped out and tested in small batches,and good results have been obtained.