Superconducting Switch System Using Variable Inductance Coupler
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Solution Overview
Problem
Conventional microwave, electro-mechanical, and electronic switches are not compatible with on-chip integration and cryogenic operation of superconducting electronic circuits due to incompatible fabrication processes and high power dissipation, and tunable filters using high temperature and low temperature superconductors suffer from high return loss, limited bandwidth, and poor out-of-band isolation in switching applications.
Innovation Solution
A superconducting switch system utilizing a variable inductance coupler, specifically a Superconducting Quantum Interference Device (SQUID) with a Josephson junction, that changes inductance based on applied flux to control signal coupling and decoupling between filter network sections, allowing for efficient switching between 'ON' and 'OFF' states with improved bandwidth and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microwave, electro-mechanical, and electronic switches are used, then switching function is provided, but compatibility with on-chip integration and cryogenic operation is poor and power dissipation is high
Solution Approach 1:
The patent changes the operating parameters by using superconducting materials that operate at cryogenic temperatures, fundamentally altering the thermal and electrical parameters to achieve both low power dissipation and compatibility with superconducting circuits. The switch utilizes the superconducting-to-normal transition at specific temperature and current thresholds to achieve switching functionality with minimal power consumption.
Solution Approach 2:
The patent replaces mechanical and conventional electronic switching mechanisms with a superconducting-based switching mechanism that relies on quantum mechanical effects (Josephson effect) and superconducting phase transitions, eliminating the need for mechanical moving parts and conventional semiconductor-based switching that are incompatible with cryogenic operation.
2Temperature
If tunable filters using high temperature and low temperature superconductors are used, then superconducting operation is achieved, but return loss is high, bandwidth is limited and out-of-band isolation is poor
Solution Approach 1:
The patent implements dynamic control of the filter characteristics by using a superconducting switch that can transition between superconducting and normal states. This dynamic switching capability allows the filter to be reconfigured between different operational states (passband and stopband), enabling adjustable bandwidth and improved isolation characteristics that are not achievable with fixed superconducting filters.
Solution Approach 2:
The patent segments the filter into multiple sections with a controllable switch element inserted within the signal path. This segmentation allows independent control of different filter sections, enabling optimization of return loss, bandwidth, and out-of-band isolation by selectively activating or deactivating specific filter sections through the superconducting switch.
3Use of energy by moving object
If superconducting switches are used to achieve low power dissipation, then power efficiency is improved, but switching control compatibility with single flux quantum technologies is limited
Solution Approach 1:
The patent designs the superconducting switch to serve multiple functions: it provides low-power switching while also being controllable by single flux quantum (SFQ) signals. The switch structure is engineered to respond to both direct current bias control and pulsed flux control, making it universally applicable in superconducting digital logic systems that use SFQ technologies for control signals.
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 achieves a better than 20 dB on/off ratio and up to 40% bandwidth with input powers up to -85 dBm, providing effective switching compatible with single flux quantum (SFQ) control and cryogenic operation.
Implementation Method 1
A superconducting switch system utilizing a variable inductance coupler, specifically a Superconducting Quantum Interference Device (SQUID) with a Josephson junction, that changes inductance based on applied flux
Implementation Method 2
A bias element is inductively coupled to the SQUID to induce current in the SQUID
Data Source
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AI summary
A superconducting switch system is provided that includes a filter network having an input portion and an output portion, and a variable inductance coupling element that couples the input portion to the output portion. The variable inductance coupling element has a first inductance that allows a desired portion of an input signal to pass from the input portion to the output portion as an output signal, and a second inductance state that suppresses the input signal from passing from the input portion to the output portion. The superconducting switch system further comprises a switch controller configured to control the switching of the variable inductance coupling element between the first inductance state and the second inductance state.