James Buckwalter

About

James Buckwalter is a Professor in the Department of Electrical and Computer Engineering at UC Santa Barbara. His research interests include high-speed mixed-signal circuits, RF and millimeter-wave integrated circuits and systems, photonics, optoelectronic interfaces, and CMOS and III-V integrated circuits. He is associated with the Wireless and Optoelectronic Integrated Circuits Lab and is based in the Harold Frank Hall, Room 4155. His contact information includes a phone number (+1 805-893-5639), email (buckwalter@ece.ucsb.edu), and office location at 2205C Engineering Science Building. Professor Buckwalter's work focuses on advancing integrated circuit technologies and systems in the fields of high-frequency electronics and photonics, contributing to the development of innovative solutions in these areas.

Research topics

• Electrical engineering
• Computer Science
• Electronic engineering
• Engineering
• Physics
• Optics
• Telecommunications
• Optoelectronics
• Materials science
• Computer hardware

Selected publications

• High Linearity and High Gain Performance of N-Polar GaN MIS-HEMT at 30 GHz

  IEEE Electron Device Letters · 2020 · 92 citations

  Though GaN HEMTs have primarily been used for power amplification, they are also well suited for receiver applications. In the front-end of receivers, non-linearities, in particular third-order intermodulation products lead to in-band signal distortion. The intermodulation distortion is primarily dominated by transconductance and its derivatives. In this paper, we report on N-polar GaN MIS-HEMTs able to simultaneously achieve high gain (12.7 dB) and excellent linearity performance (OIP3/P <sub x…

  DOI

• Power Consumption Analysis for Mobile MmWave and Sub-THz Receivers

  2020 · 92 citations

  Power consumption is one of the most significant technical barriers for practical millimeter wave (mmWave) communication devices for mobile applications. Communication in the higher mmWave bands above 100 GHz will face even greater challenges. This paper attempts to provide initial power estimates for mobile mmWave devices under realistic parameter values and state-of-the-art device performance characteristics to understand the performance of such systems today and guide research for the future.…

  DOI

• Analog Coherent Detection for Energy Efficient Intra-Data Center Links at 200 Gbps Per Wavelength

  Journal of Lightwave Technology · 2020 · 81 citations

  As datacenters continue to scale in size, energy efficiency for short reach (<; 2 km) links is a major factor for networks that may connect hundreds of thousands of servers. We demonstrate that links based on analog coherent detection (ACD) offer a promising path to simultaneously achieving significantly larger link budgets and improved link energy efficiency. A complete analysis is presented that considers the power consumption of all the photonic and electronic components necessary to realize…

  DOI

• First Demonstration of an O-Band Coherent Link for Intra-Data Center Applications

  Journal of Lightwave Technology · 2023 · 26 citations

  We report the first demonstration of a full O-band coherent link for intra-data center applications, including custom photonic and electronic integrated circuits for the transmitter and receiver. Full-link 112 Gbps (56 Gbaud QPSK) transmission is shown with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.1\cdot 10^{-4}$</tex-math></inline-formula> measured BER, and record baud rate 128 Gbps (64 Gbaud QPSK) tr…

  PublisherDOI

• A 50-GBaud QPSK Optical Receiver With a Phase/Frequency Detector for Energy-Efficient Intra-Data Center Interconnects

  IEEE Open Journal of the Solid-State Circuits Society · 2022 · 21 citations

  Senior authorCorresponding

  This paper describes the energy-efficient realization of a QPSK optical receiver (CoRX) for short-reach intra-datacenter interconnects based on analog coherent detection. The CoRX comprises inphase and quadrature channels for each polarization and a high-speed phase-frequency detector (PFD) that provides feedback to stabilize an optical local oscillator (LO) and maintain coherence with the received optical signal. Each receive (RX) channel consists of a transimpedance amplifier (TIA) based on a…

  DOI

Recent grants

• CAREER: Reconfigurable Traveling Wave Silicon Integrated Circuits for Millimeter-Wave Testing

  NSF · $400k · 2011–2015

• Enabling Algorithms, Signal Processing, and Circuits for Agile Cognitive Radio in CMOS Technology

  NSF · $1.1M · 2015–2019

• CAREER: Reconfigurable Traveling Wave Silicon Integrated Circuits for Millimeter-Wave Testing

  NSF · $288k · 2015–2017

Frequent coauthors

• Clint L. Schow

  University of California, Santa Barbara

  41 shared

• P.M. Asbeck

  University of California, San Diego

  37 shared

• Aaron Maharry

  University of California, Santa Barbara

  34 shared

• Hector Andrade

  29 shared

• L.E. Larson

  Providence College

  22 shared

• Luis A. Valenzuela

  Intel (United States)

  20 shared

• Cameron Hill

  University of California, Santa Barbara

  20 shared

• Jeff Shih-Chieh Chien

  University of California, Santa Barbara

  20 shared

Labs

• RF and Mixed-signal Integrated Systems LabPI

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