在串行数据通信领域中,过采样法CDR是一种便于单芯片集成、具有快速同步特点的低成本数字技术.文中经过理论分析给出了一个基于过采样技术的时钟数据恢复电路(CDR)设计.该设计采用4倍过采样技术并使用多数判决规则从输入数据位流中提取时钟和恢复数据.实验结果表明在至少1/4位宽抖动容差范围内,传输系统满足面向USB应用的差错率设计要求.
In serial data communication domain, clock and data recovery (CDR) using oversampling is a low-cost "fast retiming" technique that can be implemented as monolithic circuits using the standard digital CMOS process. This paper presents a CDR circuit based on oversampling. The design uses 4x oversampling rate, that is, an FSM is constructed to get four equidistant samples per bit cell. Data are then extracted from input data dreams using a majority decision algorithm. Simulation results show that the specified bit error rate oriented to USB2.0 is achieved in the presence of at least 1/4 bit cell jitter. It is believed that the analysis and design technique are useful for other serial data communication of computer peripherals.