Single Flux Quantum Circuit Biasing Without Static Power Loss
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Solution Overview
Problem
Superconducting Josephson junction circuits face significant power dissipation due to static power consumption, which is not only wasteful but also requires additional cooling, limiting their efficiency and performance.
Innovation Solution
The introduction of a superconducting single flux quantum circuit design that eliminates resistors providing bias current, instead using a superconducting biasing transformer to manage the bias current through AC biasing, reducing the number of Josephson junctions required and minimizing static power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistors are used to provide bias current to Josephson junctions, then the junctions can operate, but static power dissipation occurs continuously
Solution Approach 1:
The patent applies periodic AC biasing instead of continuous DC biasing through resistors. The bias current is applied periodically at the critical current level, allowing the Josephson junction to operate reliably only during the bias pulse duration. This eliminates continuous static power dissipation while maintaining junction operation during the periodic bias cycles, directly resolving the contradiction between reliable operation and energy loss.
2Loss of energy
If more Josephson junctions are used to eliminate static power dissipation, then power consumption is reduced, but circuit complexity increases
Solution Approach 1:
The patent changes the biasing parameter from continuous DC to periodic AC at critical current levels. This parameter change allows the circuit to use fewer Josephson junctions (sometimes even a single junction) while eliminating static power dissipation. The periodic biasing parameter enables the system to achieve both low power consumption and reduced device complexity simultaneously.
3Loss of energy
If static power dissipation is reduced, then cooling requirements are reduced, but the circuit design becomes more complex
Solution Approach 1:
The patent employs self-service mechanisms where the Josephson junction's own critical current characteristics are exploited to generate the necessary biasing conditions. The periodic biasing scheme uses the junction's inherent properties to automatically regulate its operation, eliminating the need for complex external bias control circuits and reducing overall design complexity while maintaining low power dissipation.
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 design significantly reduces power consumption and heat generation, enhancing the efficiency and performance of superconducting circuits by eliminating unnecessary power dissipation and the need for excessive cooling.
Implementation Method 1
a superconducting single flux quantum circuit comprising at least one Josephson junction which is provided with an input pulse and which flips and provides an output pulse when the current through the Josephson junction exceeds a critical value
Implementation Method 2
superconductor circuits which utilize superconducting Josephson junctions
Data Source
Figure 1~1A
Figure 2~2A
Figure 3~3A
AI summary
Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.