Josephson Flux-Shuttle Current Source for Low-Power DC Bias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Superconducting digital circuits using Josephson junctions face challenges with spurious magnetic fields and heat due to high power dissipation in bias resistor networks, which dominate the power budget and are inefficient.
Innovation Solution
A Josephson current source system with a flux-shuttle loop and a flux injector system that uses an AC clock signal to sequentially trigger Josephson junctions, generating a DC output current through an output inductor, and automatically deactivates/reactivates based on current amplitude, reducing static power consumption and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias resistor network is used to provide DC bias current to Josephson junctions, then the junctions can be biased, but spurious magnetic fields and heat are generated due to high power dissipation
Solution Approach 1:
The patent employs periodic AC clock signals to drive the flux-shuttle loop, which sequentially triggers Josephson junctions to generate DC output current. This periodic action replaces the continuous DC bias from resistor networks, enabling the system to consume approximately zero power in the quiescent state while eliminating continuous heat generation and spurious magnetic fields.
Solution Approach 2:
The patent substitutes the passive electrical bias resistor network with an active flux-shuttle loop system using Josephson junctions and AC clock signals. This substitution transitions from a resistive power-dissipating system to a superconducting system that leverages quantum effects (Josephson effect) to generate current with minimal power consumption.
2Reliability
If a bias resistor network is used to provide DC bias current, then the junctions can be biased, but spurious magnetic fields are generated
Solution Approach 1:
The periodic AC clock signal driving the flux-shuttle loop creates time-varying currents that generate controlled magnetic flux rather than continuous spurious fields. The sequential triggering of Josephson junctions produces a coherent DC output current without the random thermal noise and spurious magnetic fields characteristic of resistive bias networks.
3Power
If the flux-shuttle loop is continuously activated, then DC output current can be generated, but power consumption increases
Solution Approach 1:
The flux injector system incorporates feedback control that automatically deactivates the flux-shuttle loop when the DC output current reaches a predetermined threshold and reactivates it when the current drops. This feedback mechanism ensures the system generates only the necessary current, maintaining a quiescent state with approximately zero power consumption when the current demand is satisfied.
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 system efficiently generates a DC output current with minimal power dissipation, maintaining a quiescent state that consumes approximately zero power, thus improving energy efficiency and reducing heat generation compared to traditional resistance-based sources.
Implementation Method 1
Each of the plurality of stages includes at least one Josephson junction. The flux-shuttle loop can be configured, when activated, to sequentially trigger the Josephson junctions in each of the plurality of stages about the flux-shuttle loop in response to an inductively-coupled AC clock signal to generate a DC output current
Implementation Method 2
The clock transformers are configured to inductively couple an AC clock signal to the flux-shuttle loop, such that the AC clock signal provides a bias current in the flux-shuttle loop
Implementation Method 3
an output inductor configured to provide the DC output current based on the voltage pulses provided from each stage
Data Source
AI summary
One embodiment describes a Josephson current source system. The system includes a flux-shuttle loop comprising a plurality of stages arranged in a series loop. Each of the plurality of stages includes at least one Josephson junction. The flux-shuttle loop can be configured, when activated, to sequentially trigger the at least one Josephson junction in each of the plurality of stages about the flux-shuttle loop in response to an inductively-coupled AC clock signal to generate a DC output current provided through an output inductor. The system also includes a flux injector system that is configured to activate the flux-shuttle loop. The flux injector system is further configured to automatically deactivate the flux-shuttle loop in response to an amplitude of the DC output current increasing to a predetermined deactivation threshold.