A Digital Clock and Data Recovery Architecture for Multi-Gigabit/s Binary Links

Abstract

In this tutorial paper, we present a general architecture for digital clock and data recovery (CDR) for high-speed binary links. The architecture is based on replacing the analog loop filter and voltage-controlled oscillator (VCO) in a typical analog phase-locked loop (PLL)-based CDR with digital components. We provide a linearized analysis of the bang-bang phase detector and CDR loop including the effects of decimation and self-noise. Additionally, we provide measured results from an implementation of the digital CDR system which are directly comparable to the linearized analysis, plus measurements of the limit cycle behavior which arises in these loops when incoming jitter is small. Finally, the relative advantages of analog and digital implementations of the CDR for high-speed binary links is considered