A 4 x 5-Gb/s 1.12-μs Locking Time Reference-Less Receiver With Asynchronous Sampling-Based Frequency Acquisition and Clock Shared Subchannels

A 4x5-Gb/s reference-less receiver is proposed in a 0.13-mu m CMOS technology. In the proposed reference-less clock and data recovery (CDR) circuit, asynchronous sampling-based frequency acquisition is proposed to achieve a fast frequency locking, and VCO calibration is proposed to attain a constant loop bandwidth. To reduce noise caused by multiple VCOs, a clock signal is forwarded from the main channel to the subchannels, and skews between the channels are compensated by a skew compensation algorithm. In the main channel, the reference-less CDR achieves a 1.12-mu s locking time, and the measured standard deviation of VCO gain is reduced from 0.33 to 0.08. The recovered clock jitter in the main channel is 1.591 ps(rms), and the power consumption of the main channel and the subchannels are 3.53 and 2.16 mW/Gb/s, respectively.