Clock Jitter in SerDes: Eye Diagram Impact and PLL Strategies

Introduction

In high-speed serial interfaces, clock jitter is a fundamental challenge. The timing accuracy of transitions directly determines the signal-to-noise margin at the receiver. In precision IC design, jitter poses a critical constraint on achievable data rates and bit-error ratios.

This article explores how clock jitter affects the eye diagram opening in SerDes transceivers. We will examine the decomposition of random jitter (RJ) and deterministic jitter (DJ), strategies for low-noise PLL implementation, and effective power supply filtering approaches to preserve signal integrity.

Impact of Clock Jitter on Eye Diagrams

The eye diagram is a superposition of many symbol periods. Clock jitter causes horizontal movement in the crossing points, effectively reducing the