A 200–256-GS/s Current-Mode 4-Way Interleaved Sampling Front-End With Over 67-GHz Bandwidth Using a Slew-Rate Insensitive Clocking Scheme

Authors:
Publisher website
Google Scholar
Abstract
The surge of data traffic in emerging optical communication applications has led to the development of ultra-fast transceivers with extremely high data throughput. The latest transmitters and receivers aim for symbol rates of 150–200 Gbaud or even higher, striving to achieve bandwidths beyond 70 GHz. However, the current state-of-the-art analog-to-digital converters (ADCs) in advanced CMOS-FinFET technologies can only handle limited analog input bandwidths and sampling rates, becoming a bottleneck in enhancing the overall speed of the transceiver. A time-interleaved sampling front-end acting as an input signal de-interleaver can reduce the sub-ADCs’ analog bandwidth and clock jitter requirements. This article investigates a current-mode time-interleaved 1–4 sampling front-end operating at 200–256 GS/s, using a 50% duty-cycle slew-rate insensitive quadrature clocking strategy. The chip was fabricated in a 130-nm SiGe BiCMOS technology and was characterized by single-tone sinusoidal and non-return-to-zero/pulse-amplitude-modulation-4-level (NRZ/PAM-4) measurements at 200, 224, and 256 GS/s. The chip demonstrates a 3-dB analog input bandwidth beyond 67 GHz and a signal-to-noise-and-distortion ratio (SNDR) of 27.8–34.1 dB (at 200 GS/s), 25–36.3 dB (at 224 GS/s), and 22.3–39 dB (at 256 GS/s) for input frequencies from 1.1 to 67.1 GHz. The analog demultiplexing functionality of the sampling front-end is demonstrated with 100, 112, and 128 Gbaud NRZ/PAM-4 measurements. The complete chip consumes a power of 1.1 W at 256 GS/s, corresponding to an efficiency of 4.3 pJ/sample or 4.3 pJ/bit (with two samples per symbol).
Funding Information
  • imec High-Speed Transceiver and Coherent Transceiver Programs, European Union (EU)-Funded H2020 Projects POETICS (871769)
  • Special Research Fund (BOF) of Ghent University
  • Research Foundation Flanders

This publication has 29 references indexed in Scilit: