An Anti-Harmonic-Lock Frequency Detector for Continuous-Rate Clock and Data Recovery

This paper presents a frequency detector (FD) for a continuous-rate clock and data recovery (CDR). The study analyzes the harmonic locking issue occurring in wide-range CDR and introduces the FD to prevent harmonic lock. It achieves anti-harmonic lock and fast lock time using coarse and fine frequency tuning. The conventional single-loop CDR incorporating the proposed FD is implemented and simulated in 65-nm CMOS technology. The capture range is 4-to-9 Gb/s and the locking time is shorter than 2 μs for the maximum frequency offset of 7 GHz.