Superconducting Logic Gate Topology for Low-Coupling Dual Outputs
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Solution Overview
Problem
Existing CMOS technology is nearing maturity and requires alternatives that can enhance performance in terms of speed, power dissipation, computational density, and interconnect bandwidth, particularly in superconducting Josephson junction logic circuits.
Innovation Solution
A two-input two-output superconducting gate system utilizing Josephson junctions and bias inductors to perform logic-OR and logic-AND operations, with a transformer providing bias flux current and negative bias inductors to manage Josephson junctions, allowing for concurrent logic functions without requiring simultaneous input pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional superconducting logic circuits are used, then logic operations can be performed, but the circuit size is large and mutual inductive cross-coupling is high
Solution Approach 1:
The patent combines multiple logic functions (AND, OR, NOT) into a single gate structure that processes two inputs simultaneously. The gate integrates multiple Josephson junctions and inductors to perform concurrent logic operations, reducing the overall circuit area while minimizing mutual inductive cross-coupling between different logic functions through shared magnetic flux pathways.
Solution Approach 2:
The superconducting gate is designed as a universal logic element that can perform multiple logic functions (AND, OR, NOT) depending on the configuration of inputs and feedback paths. This multi-functionality reduces the total number of separate logic gates needed, thereby decreasing circuit area and reducing mutual inductive interference between adjacent gates.
2Adaptability or versatility
If separate logic gates are used for each function, then logic operations can be performed independently, but the device complexity increases
Solution Approach 1:
The gate structure implements a universal logic element capable of performing AND, OR, and NOT operations through different input combinations and feedback configurations. This reduces device complexity by replacing multiple specialized gates with a single multi-functional gate, while maintaining full adaptability for various logic operations.
Solution Approach 2:
The gate employs dynamic feedback mechanisms where the output of one logic function can be fed back to modify the behavior of other logic functions within the same gate. This dynamic reconfigurability allows the same physical structure to adapt to different logic operation requirements without increasing hardware complexity.
3Reliability
If larger inductors are used for storage, then persistent current is maintained better, but the circuit area increases
Solution Approach 1:
The patent combines the storage function with the logic operation function by integrating inductors into the logic gate structure itself. The inductors serve dual purposes: maintaining persistent current for reliable logic state storage and participating in the magnetic flux modulation required for logic operations. This eliminates the need for separate large storage inductors, reducing circuit area while maintaining reliability.
Solution Approach 2:
The design optimizes the inductor parameters (inductance value, coupling coefficient) to achieve the minimum size required for reliable persistent current maintenance. By carefully selecting and tuning these parameters, the inductors maintain adequate storage capability while occupying minimal area within the compact gate structure.
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 improved parametric operating margins and a more compact design by reducing mutual inductive cross-coupling, enabling efficient logic operations with reduced storage inductor size and maintaining logic functions across clock cycles.
Implementation Method 1
superconducting Josephson junctions
Implementation Method 2
a transformer that interconnects the first output and a low-voltage rail. The transformer further comprises a primary winding through which a flux bias current is applied to add a bias to the first Josephson junction
Data Source
Figure 1~2
Figure 3
AI summary
One example includes a superconducting gate system. The system includes a first input that is configured to provide a first input pulse and a second input that is configured to provide a second input pulse. The system also includes a gate configured to provide a first output pulse at a first output corresponding to a first logic function with respect to the first and second input pulses and based on a positive bias inductor and a first Josephson junction that are each coupled to the first output. The gate is also configured to provide a second output pulse at a second output corresponding to a second logic function with respect to the first and second input pulses and based on a negative bias inductor and a second Josephson junction that are each coupled to the second output.