Accurate Characterization for Continuous-Time Linear Equalization in CMOS Optical Receivers

Diaaeldin Abdelrahman, Mohamed Atef

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Recently published CMOS optical receivers consist of a limited-bandwidth first-stage transimpedance amplifier (TIA) followed by an equalizer. Limiting the TIA's bandwidth improves the gain and reduces the noise but introduces a significant inter-symbol interference (ISI) that is dealt with by the subsequent equalizer. Continuous-time linear equalizer (CTLE) is a commonly used equalizer in both electrical and optical links. However, recent research reported different findings about CTLE-based optical receivers. Some research papers concluded that CTLEs boost high-frequency noise compared to a full-bandwidth design. Other publications reported that high-frequency noise remains unaffected while white noise is significantly reduced. This work aims to solve this discrepancy by presenting an accurate analysis for CTLE-based optical receivers considering noise, gain, and jitter. We show that the noise performance depends on the pole/zero locations of the limited-bandwidth (LBW)-TIA and the follow-on equalizer. A properly designed CTLE-based receiver achieves a 2.5 × higher gain and a 1.74× better noise than the full-bandwidth design. The CTLE is also compared to the well-known decision feedback equalizer (DFE). The noise performance of the CTLE-based receiver lies between that of finite and infinite impulse response DFE-based receivers but achieves better gain than both architectures.

Original languageEnglish
Pages (from-to)129019-129028
Number of pages10
JournalIEEE Access
Publication statusPublished - 2022


  • Optical receiver
  • equalizer
  • jitter
  • noise
  • transimpedance amplifier

ASJC Scopus subject areas

  • General Engineering
  • General Computer Science
  • General Materials Science


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