Reasearch And Design Of Embeded SRAM Used For TFT-LCD Driver IC Of Mobile Phone

Displayer driver Integrated Circuit (IC) for Thin Film Transistor Liquid Crystal Display(TFT-LCD) of Mobile phone is a IC chip that integrates multifunction displayer drive circuitsthrough System on a Chip (SOC) technology to obtain higher density and lower powerconsumption. Nowadays, the embedded Static Random Access Memory(SRAM) in Mobilephone displayer driver ICs used as store pixel data is good for decreasing the total area ofsystem circuits and improving system performance. However, the SRAM possesses a largeproportion of the whole chipset both in the power dissipation and chipset area, and its speedhas great influence on the whole performance of ICs. Therefore, increasing the SRAM’sspeed in the condition of the low power dissipation and high integration is significant forimproving the performance of driver ICs.This work analyzed the basic structure of SRAM circuit and the operation principle ofeach sub-circuit. Based on these works, the overall design scheme of the SRAM wasproposed, and a SRAM with the capacity of320x480x18bits and its timing control circuitwas designed based on the0.18μm standard CMOS technology. Finally, the function andperformance of the SRAM was verified through simulation. The design was focused onimproving the operation speed of SRAM circuit by using the method of timing cooperatingwith control circuits.The designed SRAM could be read and written simultaneously to escape the timingconfliction of the two operations by using time-division technology of fixed time in readoperation and write operation. In order to reduce pre-charge time and enhance its operationspeed, the pre-charge circuit was designed to charge the Bit-Line when there was no readoperation or write operation in SRAM. Sense amplifier arrays were used to latch data duringthe line scan operation, and thus the design achieved the inversing operation of display datawith the output mode by an address selection data.This design had realized the plan of read operation and write operation, which wasproven by timing simulation using Hsim and Hspice tools. The SRAM could work in thesituation of successive write operation with the speed of50MHz, and its write-in andread-out data were correct. Therefore, this design could partly improve effective timing utilization rate and the processing speed of mobile phone displayer driver IC of TFT-LCD.