Reconfigurable Clockless SFQ Logic for Relaxed Timing Constraints
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Solution Overview
Problem
Clocked SFQ logic architectures face challenges with cumbersome clock distribution networks and strict timing requirements, particularly in VLSI digital design, which are not addressed by self-resetting clockless SFQ gates.
Innovation Solution
Implementing reconfigurable clockless SFQ logic circuits with a configurable logic gate that holds an internal state, allowing for clockless operation and eliminating the need for clock signals and self-resetting circuitry, thereby relaxing timing constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clocked SFQ logic architectures are used, then logic operations can be performed with defined timing, but clock distribution networks become cumbersome and power dissipation increases
Solution Approach 1:
The patent extracts and removes the clock distribution network from the SFQ logic architecture by implementing self-resetting circuitry directly within the logic gates. This eliminates the need for external clock signals and their associated distribution infrastructure, thereby reducing device complexity while maintaining reliable operation through intrinsic timing control.
Solution Approach 2:
The logic gates are equipped with self-resetting circuitry that automatically resets their internal states without external clock intervention. This self-service mechanism allows the gates to autonomously manage their timing and state recovery, eliminating dependence on clock distribution networks while ensuring reliable logic operation.
2Device complexity
If self-resetting clockless SFQ gates are used, then clock distribution networks are eliminated, but timing requirements are still defined by self-reset times
Solution Approach 1:
The patent implements reconfigurable logic gates where the timing characteristics and logic functions can be dynamically adjusted. By making the logic gates reconfigurable, the timing requirements are no longer fixed by hardware-defined self-reset times but can be adapted through configuration, thereby increasing timing flexibility while maintaining the elimination of clock distribution networks.
Solution Approach 2:
The logic gates utilize configurable parameters that allow adjustment of their operational characteristics including timing behavior. This parameter configurability enables the gates to adapt to different timing requirements without being constrained by fixed self-reset times, thus improving versatility while preserving the clockless architecture benefits.
3Productivity
If internal states are held in logic gates, then logic operations can be performed, but reset operations require clock signals or self-resetting circuitry
Solution Approach 1:
The patent merges the state-holding functionality with the self-resetting capability within a single integrated logic gate structure. By combining these functions, the need for separate reset circuitry is eliminated, as the gate itself performs both state retention and autonomous resetting, thereby maintaining logic operation capability while reducing overall device complexity.
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 solution enables flexible logic gate configurations without clock signals, reducing power dissipation and timing constraints, and simplifying VLSI digital design by eliminating the need for clock distribution networks and self-resetting circuitry.
Implementation Method 1
Josephson junctions (which are configured to operate as ultrafast Josephson junction switches)
Implementation Method 2
superconducting elements formed of superconducting material, such as Niobium, and operate at cryogenic temperatures (e.g., below 10 Kelvin for Niobium superconducting material)
Implementation Method 3
quantization of magnetic flux. An SFQ pulse is a voltage pulse whose time integral is equal to a discrete amount of magnetic flux, i.e., a single magnetic flux quantum, referred to herein as a 'fluxon'
Data Source
AI summary
A device comprises a clockless single flux quantum (SFQ) logic circuit comprising input and output stages and a configurable logic circuit which comprises at least one configurable logic gate that holds an internal state. The input stage comprises a signal input converter circuit which receives a two-level input signal and generates an SFQ pulse on each rising and falling edge of the two-level input signal. The configurable logic circuit performs logic operations using SFQ pulses from the input stage, and outputs SFQ pulses to the output stage which comprises a signal output converter circuit that converts each output SFQ pulse into a two-level output signal. The signal output converter circuit holds an internal state. The configurable logic circuit is configurable to implement a logic function by initializing the internal state of the signal output converter circuit and/or the internal state of the at least one configurable logic gate.