An Improved Wide-Band Referenceless CDR with UP Pulse Selector for Frequency Acquisition

Abstract

This paper presents a wide-band referenceless clock and data recovery (CDR) with a UP pulse selector in frequency acquisition scheme that decreases frequency tracking time. By combining coarse and fine frequency tracking loops, the CDR obtains a capture range from 0.3 Gb/s to 3.2 Gb/s, which is limited only by the operating frequency of the voltage control oscillator (VCO). A digital frequency band selector for the wideband VCO is presented as well to select an exact frequency band of the VCO. The proposed CDR is implemented in 180 nm CMOS process, achieves the frequency acquisition time of 0.8 μs with tracking range of 300 MHz and 10-ps peak-to-peak jitter of recovery clock at 3 Gb/s.