This work presents a new frequency acquisition method using semi-rotational frequency detection (SRFD) algorithm for a reference-less clock and data recovery (CDR) in a serial-link receiver. The proposed SRFD algorithm classifies the bang-bang phase detector(BBPD) outputs to estimate the current phase state, and detects the frequency mismatch between the input data and the sampling clock. The VCO-track path in a digital loop filter (DLF) enables online calibration of a drifted frequency of VCO caused by temperature or voltage variation after a frequency acquisition. The proposed algorithm can be implemented as a digitally-synthesized circuit, lowering design efforts for referenceless CDRs. A 10 Gbps transceiver IC with the proposed algorithm, fabricated in a 65nm CMOS process, demonstrates successful recovery of the input phase without any reference clock.
@article{arxiv.1905.00273,
title = {A fully-digital semi-rotational frequency detection algorithm for bang-bang CDRs},
author = {Soon-Won Kwon and Hanho Choi and Younho Jeon and Bongjin Kim and WooHyun Kwon and Homin Park and Kyeongha Kwon and Gain Kim and Hyeon-Min Bae},
journal= {arXiv preprint arXiv:1905.00273},
year = {2019}
}