Doctor of Philosophy Physics

May 1997

Ultra-low-power RSFQ Devices and Digital Autocorrelation of Broadband Signals

Alexander Vyacheslavovich Rylyakov

Abstract:

Advisor: Professor Konstantin K. Likharev

This thesis addresses the problem of minimizing the power dissipated in high-speed superconductor (RSFQ) circuits with application to the design of unique device instrumentation for physics experimentation and other applications. A working prototype of one such device, an ultra-wide-band ( ), ultra-low-power ( per channel) all-digital autocorrelator for millimeter-wave radioastronomy has been designed and successfully tested. The main effect limiting power dissipation in RSFQ circuits, - the interaction of Josephson junctions through the biasing line, has been studied theoretically for a simple model. A detailed experimental study of the operating margins of a typical RSFQ circuit, a low-power XOR gate as a function of both bias voltage and clock speed has been performed. The experimental results include:

• demonstration, for the first time, of a 23 nanowatt XOR gate operating at frequencies of up to ;
• measurement, for the first time, of bias and frequency dependences of error rates (in the range) at both lower and upper bias margins of an RSFQ cell;
• observation, for the first time, of the minimum error rate at the optimal bias.

Another major building block of the autocorrelator - an array of 8 low-power T flip-flop binary counters dissipating 30 nanowatt each was shown to operate at frequencies of up to . Two different designs of an RSFQ autocorrelator have been proposed and their main building blocks successfully tested at low-frequency at different levels of integration. A fully integrated 16-channel autocorrelator with 10 T flip-flop prescalers per channel, on-chip high-speed clock and quantizer (total number of Josephson junctions: 1636) was successfully tested at clock speeds of up to .

• Contents
• List of Figures
• List of Tables
• Introduction
  • RSFQ Digital Technology
    • Basic Considerations
    • Principal Components of RSFQ Circuits
    • Main building blocks of RSFQ devices
      • Josephson transmission line
      • Splitter
      • Confluence buffer (merger)
      • D flip-flop
      • I/O interface
    • Present day state of the art in the RSFQ technology
  • Autocorrelation Spectroscopy
    • Basic Considerations
    • Existing Digital and Analog Autocorrelators
  • Formulation of the Problem
• Power Dissipation in RSFQ circuits [40]
  • Introduction
  • Simple Model of an RSFQ Biasing Line
    • Formulation of the Model and General Solution
    • Case
    • Case
    • Periodic switching
  • Discussion
• Low-power High-speed Rare-error Experiment [40]
  • Introduction
  • Block Diagram of the Experiment
  • Low-power XOR gate
  • Experimental Results
  • Discussion
• Dual-rail Asynchronous Autocorrelator Design [45]
  • Introduction
  • Block diagram
  • Digital Delay line and Multiplier.
  • Accumulators
  • Testing
  • Conclusion
• Autocorrelator Design Based on a Circular Shift Register [49]
  • Introduction
  • Design
    • Block Diagram
    • Digital Delay Line with Multipliers
    • Low-power T Flip-flop Prescalers
  • Testing
  • Conclusion
• Fully Integrated 16-channel 11-GHz Autocorrelator
  • Block Diagram
  • Experimental Results
  • Discussion
• Conclusion and Future Work
• References
• PSCAN dimensionless system of units
• Hierarchical description of RSFQ circuits
• Cadence-Based Design of RSFQ Circuits
  • RSFQ Design Process
  • RSFQ-specific Components of the Cadence-Based Environment
• About this document ...