RQL A-and-Not-B Gate Using SFQ Pulses to Eliminate Static Power
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Solution Overview
Problem
CMOS technology-based digital circuits face limitations in device size and power consumption, particularly due to static power dissipation and current leakage even when inactive, leading to inefficiencies in high-performance digital systems.
Innovation Solution
The implementation of superconducting logic-based circuits using Josephson junctions and single flux quantum (SFQ) pulses, which enable low-power operation by eliminating static power dissipation and using alternating current (AC) power, thereby reducing power consumption and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If CMOS technology is used for digital circuits, then device integration and switching speed are achieved, but static power dissipation and current leakage occur even when circuits are inactive
Solution Approach 1:
The patent changes the fundamental operating parameters from DC voltage (CMOS) to AC current (superconducting logic), and from voltage-based switching to flux quantum-based switching. This parameter transformation eliminates static power dissipation while maintaining high-speed operation through the use of Josephson junctions and single flux quantum pulses.
Solution Approach 2:
The patent replaces the electronic field-based CMOS switching mechanism with a superconducting quantum mechanical system. Josephson junctions utilize quantum tunneling effects and macroscopic quantum phenomena to achieve switching, substituting the traditional semiconductor field effect with superconducting quantum dynamics.
2Productivity
If CMOS circuits operate at high clock speeds, then processing performance is improved, but power consumption increases due to dynamic and static power loss
Solution Approach 1:
The patent employs periodic AC current excitation at specific frequencies to trigger Josephson junctions, replacing continuous DC operation with pulsed periodic action. This allows high-speed processing through rapid periodic switching while minimizing average power consumption by maintaining superconducting state only when needed.
Solution Approach 2:
The patent fundamentally changes the energy carrier from DC voltage to AC current, and from electron flow to flux quantum propagation. This parameter change enables high-productivity operation through fast flux quantum switching while eliminating static power dissipation inherent in DC-biased CMOS systems.
3Duration of action of stationary object
If DC voltage is used to power CMOS circuits, then continuous operation is maintained, but current leakage occurs even when circuits are inactive
Solution Approach 1:
The patent replaces continuous DC voltage application with periodic AC current pulses. The superconducting circuit operates continuously in the zero-resistance state but only consumes energy during brief periodic excitation pulses, eliminating continuous current leakage while maintaining readiness for operation.
Solution Approach 2:
The superconducting circuit maintains its own persistent current state without external DC bias, using the inherent properties of the superconducting loop and Josephson junctions to sustain operation. The system serves itself by maintaining quantum coherence and flux states without continuous external energy input, eliminating leakage current.
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 superconducting logic-based circuits achieve zero static power dissipation and efficient power usage by employing AC power and Josephson junctions, resulting in reduced power consumption and enhanced performance compared to traditional CMOS technology.
Implementation Method 1
a first Josephson junction (JJ) coupled to receive the first set of SFQ pulses
Implementation Method 2
receiving a first set of single flux quantum (SFQ) pulses via a first input terminal
Data Source
AI summary
Superconducting circuits-based devices and methods, including reciprocal quantum logic (RQL) based devices and methods are provided. In one example, a circuit for an A-and-not-B gate including an output terminal, a first input terminal for receiving a first set of single flux quantum (SFQ) pulses, and a second input terminal for receiving a second set of SFQ pulses is provided. The circuit further includes a first Josephson junction (JJ) coupled to receive the first set of SFQ pulses. The circuit further includes a second JJ, where the second JJ when positively biased is configured to negatively bias the first JJ such that the circuit is configured to not pass the first set of SFQ pulses to the output terminal only when the second set of SFQ pulses have arrived at the second input terminal prior to an arrival of the first set of SFQ pulses at the first input terminal.