Josephson Inverter Gate Without Large Signal Transformers
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Solution Overview
Problem
Existing techniques for signal inversion in phase-mode logic circuits, such as reciprocal quantum logic (RQL) superconducting logic circuits, rely on physically large and high-efficiency transformers, which are inefficient and difficult to implement effectively.
Innovation Solution
The development of Josephson inverter gate circuits using half-twisted or floating Josephson transmission lines with DC flux bias injection, eliminating the need for large transformers by inverting signal phases directly through Josephson junctions, allowing for efficient logical and polarity inversion without high-efficiency transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transformers are used for signal inversion in RQL superconducting logic circuits, then signal inversion can be achieved, but the circuit size increases and fabrication complexity increases
Solution Approach 1:
The patent removes the transformer component from the signal inversion circuitry. Instead of using a transformer to invert signals, the invention uses a half-twisted Josephson transmission line where the signal inversion is achieved through the topological structure and phase evolution along the transmission line, eliminating the need for physically large transformer components.
Solution Approach 2:
The patent replaces the electromagnetic transformation mechanism (mechanical/electromagnetic system) with a quantum mechanical phase evolution mechanism. The half-twisted JTL uses the quantum phase properties of Josephson junctions to achieve signal inversion without requiring the physical transformer structure, thereby reducing circuit size and fabrication complexity.
2Reliability
If transformers are used for signal inversion, then signal inversion can be achieved, but device complexity increases
Solution Approach 1:
The transformer component is completely removed from the circuit architecture. The signal inversion function is extracted and redistributed across the half-twisted Josephson transmission line structure, where multiple Josephson junctions work together to achieve the inversion through their collective quantum phase behavior, simplifying the overall device structure.
Solution Approach 2:
The half-twisted Josephson transmission line serves multiple functions: it transmits signals, provides phase evolution, and achieves signal inversion, all within a single integrated structure. This multi-functionality eliminates the need for separate transformer components and reduces overall device complexity.
3Area of stationary object
If half-twisted Josephson transmission line is used, then circuit size is reduced, but initialization complexity increases
Solution Approach 1:
The patent implements preliminary initialization actions through DC flux bias injection and transient start-up procedures. Before normal operation, the half-twisted JTL is initialized by injecting specific flux biases that set the quantum phases of the Josephson junctions to the correct initial states, ensuring proper signal inversion behavior from the start.
Solution Approach 2:
The initialization process incorporates feedback mechanisms where the system monitors the phase states of Josephson junctions and adjusts DC flux biases accordingly. This feedback ensures that the half-twisted JTL reaches the correct operational state, managing the initialization complexity through active control rather than passive design.
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 enables efficient logical inversion in superconducting circuits, reducing component count and fabrication complexity while maintaining high operating margins, thus improving the efficiency and cost-effectiveness of signal inversion processes.
Implementation Method 1
a half-twisted Josephson transmission line (JTL) comprising at least four Josephson junctions arranged to propagate the input signal to an output and to invert the input signal into an output signal
Implementation Method 2
one Φ0 of current is injected into the central loop as an initializing current
Data Source
AI summary
A Josephson inverter gate circuit provides efficient implementation of polarity or logical inversion while eliminating the need for physically large high-efficiency magnetic transformers in the signal path. The circuit can consist of a half-twisted Josephson transmission line (JTL) or a JTL with an unshunted floating Josephson junction that produces two single flux quantum (SFQ) pulses when triggered by an SFQ input signal, which results in an output SFQ signal of reversed polarity. Implemented as a logical inverter, proper initialization of the circuit is accomplished within the signal inversion stage with flux biasing.