Superconducting Circuit Timing Paths for SFQ Pulse Phase Assignment

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Solution Overview

Problem

Superconducting circuits based on Josephson junctions face challenges in determining critical timing paths due to the complexity of clocking and power management, particularly in maintaining low power consumption and efficient operation, as existing methods struggle with accurately timing the arrival of single flux quantum pulses across logic gates with assigned phases.

Innovation Solution

A method and system that utilize a processor to determine whether sink terminals in superconducting circuit designs are reachable by single flux quantum pulses within a predetermined range of arrival time, allowing for the insertion or removal of Josephson transmission lines to optimize timing paths and phase assignments, thereby ensuring proper clocking and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If superconducting circuits use Josephson junctions with assigned phases for clocking, then power consumption is reduced and operation speed is improved, but determining critical timing paths becomes complex and inaccurate

Engineering Contradiction:
Improveoperation speedVSAvoidtiming path determination complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a timing model that copies the superconducting circuit structure, representing logic gates as nodes and connections as edges with timing characteristics. This model allows timing analysis without directly manipulating the complex physical circuit, simplifying the determination of critical timing paths while maintaining accuracy for circuits with assigned phases

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent introduces Josephson transmission lines as intermediary elements that provide controllable delay. These transmission lines act as mediators between logic gates, allowing precise control of signal propagation timing. By adjusting the number and characteristics of these intermediary elements, the system can compensate for timing variations and accurately determine critical paths in phased clocking circuits

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If Josephson transmission lines are inserted to adjust timing, then pulse arrival time precision is improved, but circuit complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvepulse arrival time precisionVSAvoidcircuit manufacturing difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent adjusts timing by changing parameters of existing Josephson transmission lines rather than adding complex new components. By modifying the number of junctions, line length, or geometric characteristics of existing transmission lines, precise timing control is achieved while maintaining manufacturing simplicity. This parameter-based adjustment is more easily integrated into standard superconducting circuit fabrication processes

Inventive Principle:
Principle #35Parameter changes

3Reliability

If timing analysis considers all sink terminals, then completeness of critical path identification is improved, but computational time and processing resources increase

Engineering Contradiction:
Improvecompleteness of timing analysisVSAvoidcomputational time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts and analyzes only the critical timing paths from the complete circuit, rather than performing exhaustive analysis of all possible signal paths. By identifying and focusing on the subset of paths that actually determine circuit performance, the system maintains complete and accurate critical path identification while significantly reducing computational time and processing requirements

Inventive Principle:
Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables precise determination of critical timing paths and phase assignments, optimizing the operation of superconducting circuits by ensuring timely pulse arrival and reducing power wastage, thus enhancing the efficiency and performance of superconducting logic circuits.

Implementation Method 1

Josephson junctions, which may be controlled using high speed clocks or microwave signals

Methodology Applied
Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

determining whether the first sink terminal is reachable by a single flux quantum (SFQ) pulse within a predetermined range of arrival time

Methodology Applied
Scientific EffectFlux quantization:

Data Source

PatentEP3984132B1Method and system for determining critical timing paths in a superconducting circuit design
Publication Date: 2024.08.21 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3984132B1 patent drawingFigure 1
  • EP3984132B1 patent drawingFigure 2
  • EP3984132B1 patent drawingFigure 3

AI summary

Systems and methods for determining critical timing paths in a superconducting circuit design including Josephson junctions are provided. An example method includes providing timing information concerning a plurality of source terminals of at least one logic gate coupled with a first sink terminal of the at least one logic gate. The method further includes using a processor, determining whether, in view of the timing information, the first sink terminal is reachable by a single flux quantum, SFQ, pulse within a predetermined range of arrival time based on an assigned first phase to the at least one logic gate.