A 0.5-TO-4 GBPS continuous-rate clock and data recovery circuit with bidirectional frequency detection

This paper presents a continuous-rate clock and data recovery circuit with bidirectional frequency detection. The proposed frequency detection mechanism skillfully combines rotational frequency detector and sub-harmonic tone detection techniques. By doing this, this clock and data recovery circuit achieves no locking range limitation and provides automatically bidirectional frequency detection characteristic. Based on the proposed frequency detection methodology, a proof-of-concept clock and data recovery circuit is implemented to demonstrate the feasibility and effectiveness of the proposed design. The CDR circuit is fabricated in a TSMC 0.18-μm CMOS process. The core area is 0.137 mm². The power consumption of this CDR circuit is 132.1 mW for a supply of 1.8V when input data rate is 4 Gbps. The measured peak-to-peak jitter and rms jitter of the recovered clock are 92.5 ps and 17.3 ps for a 4-Gbps 2⁷-l PRBS, respectively. Moreover, the measured peak-to-peak jitter and rms jitter of the recovered clock are 90.9 ps and 16.9 ps for a 0.5-Gb/s 2⁷-l PRBS, respectively.