Clockless DC-Powered DSFQ Logic With Self-Resetting State
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Solution Overview
Problem
Conventional dc-powered SFQ logic circuits require a clock signal for operation, which complicates VLSI digital design, especially in the RTL paradigm, and lack self-resetting capabilities without external signals.
Innovation Solution
The development of dc-powered DSFQ logic circuits with self-resetting internal states characterized by two time constants, achieved through a dynamic storage element with nonlinear magnetic flux leakage, comprising a first Josephson junction in series with a resistor and a second Josephson junction in parallel, allowing for self-resetting without external signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional SFQ logic circuits use clock signals for operation, then circuit operation is synchronized and controlled, but device complexity increases and design compatibility with VLSI methodologies decreases
Solution Approach 1:
The patent extracts and removes the clock signal requirement from SFQ logic circuits by implementing self-resetting storage loops that automatically clear their state without external clock control, thereby simplifying the circuit architecture and improving compatibility with asynchronous VLSI design methodologies
Solution Approach 2:
The storage loops are designed to self-reset automatically through intrinsic nonlinear magnetic flux leakage mechanisms, eliminating the need for external clock signals to control the reset operation, thus reducing device complexity while maintaining operational control
2Ease of operation
If traditional SFQ circuits require external signals for reset operation, then state control is precise and reliable, but ease of operation decreases due to need for external control signals
Solution Approach 1:
The storage loops incorporate nonlinear magnetic flux leakage elements that enable automatic self-resetting without external control signals, improving ease of operation while maintaining reliability through the inherent stability of the superconducting Josephson junctions and controlled flux leakage mechanisms
Solution Approach 2:
The patent utilizes changes in magnetic flux parameters and the nonlinear characteristics of Josephson junctions to enable automatic reset operation, where the system transitions between superconducting and resistive states based on intrinsic parameter changes rather than external control
3Productivity
If SFQ circuits use linear inductors for state storage, then circuit design is simple, but productivity decreases due to inability to support asynchronous evaluation of deep combinational logic
Solution Approach 1:
The patent replaces linear inductors with storage loops exhibiting nonlinear magnetic flux leakage characteristics, enabling asynchronous evaluation and dynamic hold times that support deep combinational logic networks, thereby improving productivity through faster and more flexible logic evaluation
Solution Approach 2:
The storage element transitions from a static linear inductor to a dynamic nonlinear storage loop where the hold time and flux leakage characteristics can dynamically adapt, enabling support for asynchronous evaluation and significantly increasing the depth of combinational logic that can be evaluated
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 solution enables compatibility with VLSI digital design methodologies, supports asynchronous evaluation of combinational logic networks, and improves input skew tolerance by at least one order of magnitude compared to traditional SFQ circuits.
Implementation Method 1
when a current through one of Josephson junctions in such storage loop temporary exceeds its critical current, that Josephson junction transitions to a resistive state and allows a discrete amount of magnetic flux (i.e., a single flux quantum, known as a 'fluxon') to enter or exit the storage loop
Implementation Method 2
the storage element can be characterized by nonlinear leakage of magnetic flux
Data Source
AI summary
Techniques regarding a DSFQ logic family are provided. For example, one or more embodiments described herein can comprise a system, which can comprise a dynamic single flux quantum logic circuit that has a self-resetting internal state and can be powered by direct current. Further, the self-resetting internal state can be characterized by two time constants.