Overview

A 10 Gb/s analog continuous-time equalizer with integrated clock and data recovery circuit is presented. It is designed to recover signals degraded by chromatic and polarization mode dispersion. The key components in the design are a feedforward equalizer and a decision feedback equalizer, the parameters of which are electronically adjustable. Both circuit blocks are fully described and characterized with emphasis on minimizing self-induced distortion and maximizing high-speed performance. In addition to the equalizer and the clock and data recovery, the circuit also includes an integrated automatic gain control. The circuit is implemented in a commercial 0.18 ?m SiGe BiCMOS technology and consumes 900 mW. The capacity of the equalizer to mitigate signal impairments is demonstrated using three electrically generated channels.

Keywords: equalizers; optical fiber dispersion; optical communications.

1. Introduction

With the growth of high-bandwidth applications at the premises and metro level, 10 Gb/s fiber optic links provide an attractive solution for expanding capacity in metropolitan area networks (MANs). This presents a significant challenge because 10 Gb/s signals are much more susceptible to the impairments introduced by the installed fiber, namely chromatic and polarization mode dispersion. Although passive optical solutions exist for 10 Gb/s long-haul networks, issues of cost and suitability prohibit their use in the aforementioned shorter reach applications1. For this reason, electronic techniques, in particular adaptive equalizers, have attracted a considerable amount of interest lately ^{2 5}