一种瞬态限流的全NMOS译码器设计方法

Design Method of Transient Current Limiting Full NMOS Decoder

针对低温多晶硅(low temperature poly-silicon,LTPS)和低温多晶氧化物(low temperature polycrystalline oxide,LTPO)工艺下的有机电致发光显示器(organic light emitting diode,OLED)电路设计时,驱动译码电路瞬态产生大电流引起的闩锁效应烧坏器问题,提出一种具有瞬态电流限制能力的全N增强型金属氧化物半导体(N-enhancement type metal oxide semiconductor,NMOS)场效应管的译码器电路设计方法。该方法基于树状网络进行译码和限流,利用支路简并方法进行逻辑化简,采用共源共栅结构中的输出阻抗限制译码瞬态过程的最大电流;在SMIC 180 nm CMOS工艺下完成设计,核心电路面积为470.69μm^(2)。2种不同输入条件下的仿真结果表明,采用格雷码对输入激励进行编码的5-32全NMOS译码器的功耗延迟积仅为9.77×10^(-20)J·s,比同等工艺、电源电压、温度条件下设计的CMOS 5-32译码器降低了81.8%;瞬态译码时的最大电流为11.69μA,比CMOS 5-32译码器降低了99.44%。

With respect to the latch up effect caused by large current based on low temperature polysilicon(LTPS)process and low temperature polycrystalline oxide(LTPO)organic light emitting diode(OLED)driving circuit,a decoder circuit design of full N-enhanced metal type oxide semiconductor(NMOS)field effect transistor with transient current limiting capability is proposed.This method is based on tree decoder for decoding and current limiting,and uses the branch degeneracy method for logic simplification.The output impedance of cascode structure is used to limit the maximum current in the decoding transient process.The design is completed in SMIC 180 nm CMOS process,and the core circuit area is 470.69μm^(2).The simulation results under two different input conditions show that the 5-32 full NMOS decoder using Gray code to encode the input excitation merely achieves the power delay product of 9.77×10^(-20) J·s,which is 81.8%lower than that of CMOS 5-32 decoder designed under the same process,power supply voltage and temperature.The maximum current of transient decoding is 11.69μA,which is 99.44%lower than that of CMOS 5-32 decoder.