{"title":"A Loop-Break Decision Feedback Equalizer for DAC/ADC-DSP-Based Wireline Transceivers","authors":"Donggeon Kim;Yujin Choi;Jaewon Lee;Seoyoung Jang;Sungyu Song;Matthias Braendli;Thomas Morf;Marcel Kossel;Pier-Andrea Francese;Gain Kim","doi":"10.1109/TCSI.2024.3435696","DOIUrl":null,"url":null,"abstract":"This paper presents a novel digital decision feedback equalizer (DFE) design that can relax the feedback timing constraints for analog-to-digital converter (ADC)-based high-speed wireline receivers. The proposed technique breaks the loop-unrolled DFE (LU-DFE) chain by computing multiple LU-DFE chains in parallel with all possible seed symbols, and selecting the appropriate output by the post-processing selection logic. The proposed loop-break DFE (LB-DFE) is functionally equivalent to the conventional DFE with any other implementation techniques such as LU-DFE, look-ahead DFE (LA-DFE), or direct DFE. With topographical synthesis in 28nm CMOS process, the proposed LB-DFE achieved up to 54% of DFE area saving as compared to LA-DFE with look-ahead factor (LF) of 16 for 112Gb/s PAM-4 with 875MHz DSP clock speed. The implementation feasibility and functionality are verified using ZCU111 RFSoC platform at 6Gb/s (3GS/s ADC conversion rate) with a channel exhibiting 25dB loss at 1.5GHz, demonstrating the same bit error rate (BER) performance between the LB-DFE and the LA-DFE. Equipment-based measurements using arbitrary waveform generator (AWG) and real-time oscilloscope transmitting/receiving 40GBaud PAM-4 (80Gb/s) to/from the differential cables with software 21-tap feed-forward equalizer (FFE) and LB-DFE on PC was also conducted.","PeriodicalId":13039,"journal":{"name":"IEEE Transactions on Circuits and Systems I: Regular Papers","volume":"71 11","pages":"5115-5128"},"PeriodicalIF":5.2000,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Transactions on Circuits and Systems I: Regular Papers","FirstCategoryId":"5","ListUrlMain":"https://ieeexplore.ieee.org/document/10629180/","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
引用次数: 0
Abstract
This paper presents a novel digital decision feedback equalizer (DFE) design that can relax the feedback timing constraints for analog-to-digital converter (ADC)-based high-speed wireline receivers. The proposed technique breaks the loop-unrolled DFE (LU-DFE) chain by computing multiple LU-DFE chains in parallel with all possible seed symbols, and selecting the appropriate output by the post-processing selection logic. The proposed loop-break DFE (LB-DFE) is functionally equivalent to the conventional DFE with any other implementation techniques such as LU-DFE, look-ahead DFE (LA-DFE), or direct DFE. With topographical synthesis in 28nm CMOS process, the proposed LB-DFE achieved up to 54% of DFE area saving as compared to LA-DFE with look-ahead factor (LF) of 16 for 112Gb/s PAM-4 with 875MHz DSP clock speed. The implementation feasibility and functionality are verified using ZCU111 RFSoC platform at 6Gb/s (3GS/s ADC conversion rate) with a channel exhibiting 25dB loss at 1.5GHz, demonstrating the same bit error rate (BER) performance between the LB-DFE and the LA-DFE. Equipment-based measurements using arbitrary waveform generator (AWG) and real-time oscilloscope transmitting/receiving 40GBaud PAM-4 (80Gb/s) to/from the differential cables with software 21-tap feed-forward equalizer (FFE) and LB-DFE on PC was also conducted.
期刊介绍:
TCAS I publishes regular papers in the field specified by the theory, analysis, design, and practical implementations of circuits, and the application of circuit techniques to systems and to signal processing. Included is the whole spectrum from basic scientific theory to industrial applications. The field of interest covered includes: - Circuits: Analog, Digital and Mixed Signal Circuits and Systems - Nonlinear Circuits and Systems, Integrated Sensors, MEMS and Systems on Chip, Nanoscale Circuits and Systems, Optoelectronic - Circuits and Systems, Power Electronics and Systems - Software for Analog-and-Logic Circuits and Systems - Control aspects of Circuits and Systems.