A clock and data recovery circuit with programmable multi-level phase detector characteristics and a built-in jitter monitor

Abstract

We demonstrate a clock and data recovery (CDR) circuit having a new type of a multi-level bang-bang phase detector (ML-BBPD). The gain characteristics of our ML-BBPD can be programmed by scanning the dead-zone width of a variable dead-zone BBPD in the time domain. Its linear-like gain characteristics result in less sensitive CDR performance against input jitter and process, voltage, and temperature (PVT) variations. In addition, a built-in on-chip jitter monitor can be easily implemented using our ML-BBPD. A prototype 1.25-Gb/s CDR based on our ML-BBPD with a built-in jitter monitor is realized with 0.18- $\mu{\rm m}$ CMOS technology and its performance is successfully verified with measurement.