Superconducting Circuit Layout Using Gate Tiles

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Solution Overview

Problem

Conventional superconducting IC layout techniques face challenges in efficiently placing and routing gates and active interconnects, leading to high overhead in device count, density, and performance loss, as they do not map well onto conventional place-and-route design flows.

Innovation Solution

A method and system for generating a physical layout output file for superconducting circuits, which involves determining gate tile types, positioning gate tiles and their associated Josephson junctions, assigning unassigned junctions to active interconnects, and routing wires to form active interconnect circuits, optimizing placement and routing based on netlist connections and design constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional superconducting IC layout techniques treat active interconnects similar to logic gates with custom-inductive-wires, then design flexibility is improved, but device complexity and overhead increase significantly

Engineering Contradiction:
Improvedesign flexibilityVSAvoiddevice overhead
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by creating a standardized gate tile library where each gate type includes a fixed number of unassigned Josephson junctions that can serve multiple purposes. These junctions can be assigned to form active interconnects with standardized wire routes, allowing the same gate tile structure to support both logic gates and interconnect functions, thereby reducing device complexity while maintaining design flexibility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the parameter of interconnect implementation from custom-inductive-wires to Josephson transmission lines (JTLs) formed by standardized wire routes. This parameter change allows active interconnects to be defined by routing configurations rather than custom physical structures, reducing device overhead while preserving the ability to create various interconnect topologies through software-based route definition.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If conventional layout techniques allow gates and interconnects to be drawn differently in every instance, then design adaptability is improved, but manufacturing precision and standardization deteriorate

Engineering Contradiction:
Improvedesign adaptabilityVSAvoidlayout standardization
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent segments the superconducting circuit layout into standardized gate tiles, each with a fixed structure and a defined number of unassigned Josephson junctions. This segmentation allows the circuit to be built from standardized building blocks, improving manufacturing precision and layout standardization while maintaining design adaptability through software-based configuration of how these standardized tiles are connected and configured.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses copying by replicating standardized gate tile patterns from a library. Each gate tile type can be copied and instantiated multiple times with consistent physical dimensions and Josephson junction configurations, ensuring manufacturing precision and standardization across the entire circuit while allowing different functional configurations through software assignment of the unassigned junctions.

Inventive Principle:
Principle #26Copying

3Ease of manufacture

If all connections are made through adjacent cells with standardized sizes, then manufacturing ease is improved, but device density and performance deteriorate due to high overhead

Engineering Contradiction:
Improvemanufacturing easeVSAvoiddevice density
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent moves the interconnect definition from the physical layout dimension to the logical routing dimension. By defining active interconnects as software-based wire routes that can span multiple gate tiles and layers, the solution achieves ease of manufacture through standardized gate tiles while improving device density by allowing optimized routing paths that don't require adjacent cell connections or excessive intermediary structures.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces an intermediary layer of abstraction: the place-and-route tool that assigns unassigned Josephson junctions and defines wire routes between gates. This intermediary automatically optimizes the connections between standardized gate tiles, achieving ease of manufacture through standardization while minimizing the overhead structures needed for interconnects, thereby improving device density.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach enables efficient placement and routing of superconducting circuits, reducing overhead and improving performance by standardizing gate and interconnect sizes, allowing for advanced design nodes with sub-um traces and increased vertical integration.

Implementation Method 1

determining a respective gate tile type for each gate in the netlist, wherein the gate tile type includes a gate type associated with each gate type in the netlist and a plurality of associated unassigned Josephson junctions

Methodology Applied
Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentEP3175378B1Superconducting circuit physical layout system and method
Publication Date: 2021.06.09 NORTHROP GRUMMAN SYSTEMS CORP
  • EP3175378B1 patent drawingFigure 1~2
  • EP3175378B1 patent drawingFigure 3
  • EP3175378B1 patent drawingFigure 4

AI summary

Systems and methods are provided for physical layout of superconductor circuits. The physical layout system and method is configured to place and route the superconducting circuits by first placing the gates in the form of gate tiles within unoccupied areas of a predetermined circuit design based on a netlist. Each gate tile type includes a particular gate type and a plurality of unassigned Josephson junctions that can be employed in the gates and/or the active interconnects. Inductive wires are then routed between gates incorporating and assigning the Josephson junctions to produce active interconnects between the I/O terminals of the gates based on connections defined in the netlist.