手机用TFT-LCD驱动芯片内置SRAM的研究与设计

Research and Design of Embedded SRAM Used for TFT-LCD Driver IC of Mobile Phone

内置单端口SRAM是单片集成的TFT-LCD驱动控制电路芯片中的重要模块,主要功能是存储CPU送来的一帧画面的显示图像数据以及输出数据到显示单元,其主要性能指标是存储速度和消耗功率。文章讨论了内置SRAM的分块存储结构,阐述了SRAM存储单元的设计方法。在预充电路的设计中采用了分块预充机制,既节省了功耗又保证了预充时间,同时提出了预充时位线电荷再利用设计方案,使得预充电功耗降低了1/2左右。采用0.25μmCMOS工艺设计并实现了TFT-LCD驱动控制电路芯片中的SRAM模块,其容量为418kbits。NanoSim仿真结果表明,SRAM存储单元的读写时间小于8ns,当访存时钟频率为3.8MHz时,静态功耗为0.9mW,动态功耗小于3mW。

The embedded single-port SRAM is an important module for one-chip TFT-LCD driver IC, it is used for storing a frame of image data which is sent from CPU and export image data to display unit, its main features are access speeds and power consumption. The sub-array architecture of SRAM is discussed, and a design method of SRAM cell is described. For the pre-charge circuit design, a partly pre-charge technology is used to save the power dissipation and to supply enough pre-charge time. At the same time, bit-line charge-recycling technology is proposed to reduce pre-charge power dissipation to 50 % approximately. The 418 kbit SRAM module used in TFT-LCD driver IC has been designed and realized using 0.25μm CMOS process. The results of NanoSim simulation show that the reading and writing times of SRAM are less than 8 ns, and the static power dissipation is 0. 9 mW and the dynamic power dissipation is less than 3 mW at operating frequency of 3.8 MHz.