高速采集系统的时钟端接设计与仿真

摘要

高速采集系统中常用的交流耦合端接设计没有考虑单端阻抗匹配,使得单端时钟信号产生反射,反射噪声严重时会破坏系统的准确性.为了改善反射噪声,提出了一种改进的LVPECL差分信号端接设计,将单端阻抗匹配电路引入驱动端,从而达到抑制反射噪声的效果.仿真证明,当信号频率小于500 MHz时,与常用端接设计相比,改进端接设计的接收信号过冲最大减少了10.9％,反射噪声得到抑制,提高系统的稳定性和准确度.%The common ac-coupling termination method does not consider the single-ended impedance matching, which results in breaking the accuracy of high-speed data acquisition system. To solve the problem of the reflection noise suppression, an improved LVPECL differential termination method is proposed. An impedance matching circuit is introduced, in order to suppress reflection noise. Results show that compared with the commonly ac-coupling methods,when the signal frequency is less than 500 MHz, overshoot of improved termination methods decreases maximally by 10. 9% of the Vp-p. Improved termination method has excellent reflection noise suppression, which improves effectively the accuracy of the system.