180.5Mbps-8Gbps DLL-based clock and data recovery circuit with low jitter performance

Abstract

A wide range delay-locked loop (DLL) based clock and data recovery (CDR) circuit including coarse and fine tune blocks is proposed in this paper. The coarse tune block adopts a time to digital converter and digital control delay line to widen the frequency capture range, reduce locking time and prevent the false locking problem. In the fine tune block, a novel phase detector combines the tasks of sampling and charge-pump using half rate clock. Starting-control circuit can ensure CDR takes full use of the delay range provided by voltage control delay line. Moreover, a fully analog DLL technique is applied to exploit the benefits of low skew and jitter performance. The simulation result shows the proposed CDR can cover a wide frequency range from 180.5Mbps to 8Gbps, while the peak-to-peak jitter of recovery clock is 2.7ps at 200Mbps and 1.06ps at 8Gbps. Fabricated in a 65nm CMOS process, this design dissipates 9.9mW and 22.9mW respectively at 200 Mbps and 8Gbps from a 1.2 V supply.