Josephson RQL Phase-Mode Flip-Flop Without Setup-Hold Reset
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Solution Overview
Problem
Conventional CMOS technology is nearing maturity, and there is a need for alternative digital logic solutions that offer higher performance in terms of speed, power dissipation, computational density, and interconnect bandwidth, which can be achieved through superconducting Josephson junction-based circuits.
Innovation Solution
A reciprocal quantum logic (RQL) phase-mode flip-flop is developed, incorporating a storage loop and a comparator with Josephson junctions, where data input signals are stored as single flux quantum pulses and logical clock signals are used to compare and output logical values as SFQ pulses, allowing for efficient storage and retrieval of binary data without the need for phase resetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS technology is used for digital logic implementation, then manufacturing maturity and ease of manufacture are maintained, but performance in terms of speed, power dissipation, computational density, and interconnect bandwidth is limited
Solution Approach 1:
The patent replaces conventional CMOS electronic circuits with superconducting Josephson junction-based circuits. This substitution enables single flux quantum (SFQ) logic operation, achieving higher speed (20 Gb/s or greater), lower power dissipation (around 4 nanowatts), and improved computational density while maintaining manufacturing feasibility through established superconducting fabrication processes
2Reliability
If conventional D flip-flop is used with setup and hold time requirements, then reliable data capture is achieved, but time efficiency is reduced due to mandatory stable input periods
Solution Approach 1:
The patent employs periodic clocking signals to trigger state transitions in the flip-flop. The SFQ-based flip-flop uses periodic clock pulses to capture and propagate data, eliminating the need for extended setup and hold times while maintaining reliable data capture through synchronized periodic operation
Solution Approach 2:
The patent implements continuous data flow through the flip-flop without interruption from setup/hold constraints. The SFQ logic enables data to be processed and transmitted continuously as single flux quantum pulses, removing temporal gaps that would otherwise reduce time efficiency
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
The RQL phase-mode flip-flop enables efficient storage and retrieval of binary data with reduced power consumption and increased performance, leveraging the persistence of superconducting phases across AC clock cycles, thus overcoming limitations of conventional CMOS technology.
Implementation Method 1
superconducting Josephson junctions (JJs), with typical signal power of around 4 nanowatts (nW), at a typical data rate of 20 gigabits per second (Gb/s) or greater, and operating temperatures of around 4 kelvins
Implementation Method 2
superconducting Josephson junctions (JJs)
Data Source
AI summary
A reciprocal quantum logic (RQL) phase-mode flip-flop includes a storage loop and a comparator, each of which includes Josephson junctions (JJs). A data input, provided as a positive or negative single flux quantum (SFQ) pulse, is stored in the storage loop to set the storage loop in a positive or negative state, respectively, effectively biasing an output JJ shared between the storage loop and a comparator. The data input is captured to the output upon the receipt of a logical clock SFQ reciprocal pulse pair to the comparator, when one of the pulses in the pair causes the output JJ to preferentially trigger over an escape junction in the comparator, owing to the output JJ having been biased by current in the storage loop.