AC-Powered SFQ Transmission Line for Low-Heat Ballistic Logic
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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 efficiency in terms of speed, power, computational density, and interconnect bandwidth, which superconductor-based single flux quantum (SFQ) circuitry addresses using Josephson junctions, but these circuits face challenges with heat dissipation and inefficiencies in existing logic gate designs.
Innovation Solution
The development of SFQ signal transmission lines and logic gates powered by AC sources, utilizing transformers and Josephson junctions to reduce heat dissipation and enhance efficiency, along with the implementation of inductive paths and biasing circuits to manage signal flow and prevent unwanted interactions between input pulses, resulting in fully ballistic and partially ballistic Josephson transmission lines and gates that minimize resistive damping and heat loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMOS technology is used for digital logic, then manufacturing maturity and ease of manufacture are maintained, but performance efficiency in terms of speed, power, and computational density reaches its limit
Solution Approach 1:
The patent transitions from conventional CMOS parameter ranges to superconductor-based parameters, specifically operating at cryogenic temperatures (4°K) with Josephson junctions to achieve higher speed (20 Gb/s or greater) and lower power consumption while maintaining manufacturability through established superconductor fabrication processes
2Productivity
If superconductor-based Josephson junctions are used to improve speed and power efficiency, then performance increases, but heat dissipation becomes a challenge
Solution Approach 1:
The patent extracts and eliminates resistive components from the circuit design, using purely superconducting interconnects and Josephson junctions to remove the primary source of heat dissipation (resistive heating), thereby maintaining high speed and efficiency while minimizing energy loss
Solution Approach 2:
The patent converts the challenge of cryogenic operation into a benefit by utilizing the superconducting state to achieve zero resistance, thereby eliminating heat dissipation entirely in the interconnects and enabling ultra-low power operation at 4°K
3Loss of energy
If AC power sources with transformers are used to power SFQ transmission lines, then heat dissipation is reduced and efficiency is enhanced, but device complexity increases
Solution Approach 1:
The patent introduces transformers as intermediary components that couple AC power sources to the SFQ transmission lines, enabling efficient power transfer while isolating the superconducting circuit from direct DC connections, thereby reducing heat dissipation through optimized power delivery
Solution Approach 2:
The patent employs AC power sources with periodic waveforms to drive the SFQ transmission lines, utilizing the periodic nature of the AC signal to achieve efficient power transfer and reduced heat dissipation compared to DC operation, while the transformer adapts the periodic signal to the superconducting circuit requirements
4Reliability
If biasing circuits and inductive paths are implemented to manage signal flow, then unwanted interactions between input pulses are prevented, but device complexity increases
Solution Approach 1:
The patent replaces conventional resistive biasing networks with superconducting inductive paths and Josephson junction-based biasing circuits, utilizing the unique properties of superconductors to achieve signal isolation and flow management without the heat dissipation and complexity of resistive components
Solution Approach 2:
The patent changes the operating parameters of the biasing circuits to operate in the superconducting regime, using critical current thresholds and inductive reactance to control signal flow and prevent unwanted interactions between input pulses, thereby achieving high reliability with reduced complexity compared to conventional approaches
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 proposed solution significantly reduces heat dissipation and signal loss, enabling higher performance and scalability in digital logic circuits by eliminating resistive components and optimizing signal propagation through Josephson junctions, thus achieving higher speed and lower power consumption.
Implementation Method 1
The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line.
Implementation Method 2
A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.
Data Source
AI summary
In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.