【摘要】 在跨时钟域数据传输中,常因违反触发器的建立时间和保持时间要求而产生亚稳态现象,导致数据误码。为对亚稳态发生过程进行直观观测,利用所搭建的亚稳态观测平台,在建立时间区域对TTL维持阻塞型集成边沿触发器74LS74芯片和CMOS传输门型集成边沿触发器74HC74芯片分别进行了误码测试。测试结果表明,两芯片性能接近,在建立时间0.9～1.6ns区间存在0%～100%误码过渡带,能观测亚稳态过程的直观波形。测试过程中,发现触发器输入电平上跳变时,误码率在以上区间存在稳定的单调变化曲线。当触发器输入电平下跳变时,误码率会从0%瞬变到100%,实验未观测到过渡带。输入下跳变时,当延迟参量单向递增或递减时,瞬变区域不一样,存在回差现象。更多还原

【Abstract】 In cross-clock data transmission,metastable phenomena often occur due to violation of the setup time and hold time of flip-flops,resulting in bit error.In order to observe the metastable process directly,it uses the metastable observation platform to test the bit error of TTL block holding integrated edge flip-flop 74 LS74 chip and CMOS transmission gate integrated edge flip-flop 74 HC74 chip in setup time domain.Test results show that the performance of the two chips is close,and there is a 0%～100% BER transition band in the setup time of 0.9～1.6 ns,in which the visual waveform of metastable process can be observed.It is found that there is a stable monotonic variation curve of BER in the above range when the input level of trigger jumps up.When the input level of the flip-flop jumps down,the BER changes from 0%to 100%instantaneously,and the transition zone cannot be observed.When the input jumps down and the delay parameter increases or decreases in one direction,the transient region will be different and presents a backlash phenomenon.更多还原