8.7 A 4-to-10.5Gb/s 2.2mW/Gb/s continuous-rate digital CDR with automatic frequency acquisition in 65nm CMOS

Guanghua Shu, Woo Seok Choi, Saurabh Saxena, Tejasvi Anand, Amr Elshazly, Pavan Kumar Hanumolu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Continuous-rate clock-and-data recovery (CDR) circuits with automatic frequency acquisition offer flexibility in both optical and electrical communication networks, and minimize cost with a single-chip multi-standard solution. The two major challenges in the design of such a CDR are: (a) extracting the bit-rate from the incoming random data stream, and (b) designing a wide-tuning-range low-noise oscillator. Among all available frequency detectors (FDs), the stochastic divider-based approach has the widest frequency acquisition range and is well suited for sub-rate CDRs [1]. However, its accuracy strongly depends on input transition density (0 ≤ ρ ≤ 1), with any deviation of ρ from 0.5 (50% transition density) causing 2×(ρ-0.5)×106 ppm of frequency error. In this paper, we present an automatic frequency-acquisition scheme that has unlimited range and is immune to variations in transition density. Implemented using a conventional bang-bang phase detector (BBPD), it requires minimum additional hardware and is applicable to sub-rate CDRs as well. Instead of using multiple LC oscillators that are carefully designed to cover a wide frequency range [2,3], a ring-oscillator-based fractional-N PLL is used as a digitally controlled oscillator (DCO) to achieve both wide range and low noise, and to decouple the tradeoff between jitter transfer (JTRAN) bandwidth and ring-oscillator-noise suppression.

Original languageEnglish (US)
Title of host publication2014 IEEE International Solid-State Circuits Conference, ISSCC 2014 - Digest of Technical Papers
Pages150-151
Number of pages2
DOIs
StatePublished - Apr 14 2014
Event2014 61st IEEE International Solid-State Circuits Conference, ISSCC 2014 - San Francisco, CA, United States
Duration: Feb 9 2014Feb 13 2014

Publication series

NameDigest of Technical Papers - IEEE International Solid-State Circuits Conference
Volume57
ISSN (Print)0193-6530

Other

Other2014 61st IEEE International Solid-State Circuits Conference, ISSCC 2014
CountryUnited States
CitySan Francisco, CA
Period2/9/142/13/14

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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