Thermally Isolated Ground Planes with Superconducting Couplers

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Solution Overview

Problem

Cryogenic MMICs face challenges in thermal management due to uniform temperature requirements across ground planes, leading to inefficient cooling resources and increased power dissipation as devices with different operational temperature needs are connected to a single ground plane, resulting in excessive cooling of components that only need to be maintained at higher temperatures.

Innovation Solution

The implementation of thermally isolated ground planes with a superconducting electrical coupler, where separate ground planes are electrically coupled while maintaining thermal isolation, and thermally conductive vias with varying volumes of material are used to couple these planes to a thermal sink layer, allowing for proportional heat removal based on the operational temperature requirements of different circuit sets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single ground plane is used to connect all devices, then electrical connectivity is simplified, but thermal isolation is lost causing all devices to be maintained at the most stringent temperature requirement

Engineering Contradiction:
Improveground plane structureVSAvoidoperational temperature requirement
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The ground plane is segmented into multiple thermally isolated ground planes, each serving specific devices with similar temperature requirements. This segmentation allows each ground plane to be maintained at its optimal temperature without being constrained by the most stringent temperature requirement of all devices.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Superconducting couplers are introduced as intermediary elements to electrically connect the thermally isolated ground planes. These couplers provide low-impedance electrical pathways while maintaining thermal isolation, enabling signal transmission between ground planes without significant heat transfer.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If thermally isolated ground planes are used, then cooling resources are optimized for each device temperature requirement, but electrical connectivity between ground planes becomes more complex

Engineering Contradiction:
Improvecooling resourcesVSAvoidground plane structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The electrical conductivity parameter of the coupler material is changed to superconducting state, which provides near-zero electrical resistance. This parameter change allows efficient electrical connectivity between ground planes without requiring complex multi-path routing, simplifying the overall structure while maintaining thermal isolation.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If a single ground plane maintains uniform temperature, then manufacturing is simplified, but power dissipation increases due to excessive cooling of devices that only need higher temperature maintenance

Engineering Contradiction:
Improveground plane fabricationVSAvoidpower dissipation
Core Design Contradiction:
Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The unified ground plane is segmented into multiple thermally isolated zones, each optimized for specific temperature requirements. This segmentation enables differential thermal management where each segment receives only the cooling necessary for its specific devices, dramatically reducing overall power dissipation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each ground plane segment is assigned local thermal properties and temperature requirements matching the specific devices it serves. This local quality approach ensures that cooling resources are allocated efficiently to each region based on its actual needs rather than applying uniform cooling across the entire ground plane.

Inventive Principle:
Principle #3Local quality

4Temperature

If thermally conductive vias with varying volumes are used, then proportional heat removal is achieved for different circuit sets, but manufacturing precision requirements increase

Engineering Contradiction:
Improveheat removal efficiencyVSAvoidvia material volume
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The volume parameter of thermal vias is varied to match the heat load requirements of different ground plane segments. By changing the via volume parameter proportionally to the heat load, the system achieves optimized heat removal efficiency without requiring extremely tight manufacturing tolerances, as the relationship between via volume and heat removal capacity is relatively robust.

Inventive Principle:
Principle #35Parameter changes

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 efficient thermal management by maintaining devices at their specific operational temperatures, reducing unnecessary cooling and optimizing resource usage, thereby minimizing power dissipation and enhancing the operational efficiency of cryogenic MMICs.

Implementation Method 1

A superconducting coupler electrically couples the first ground plane and the second ground plane while maintaining relative thermal isolation between the first ground plane and the second ground plane

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

a first thermally conductive via that couples the first ground plane to the thermal sink layer... to remove heat from the first set of circuits

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a second thermally conductive via that couples the second ground plane to the thermal sink layer... to remove heat from the second set of circuits

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3704739B1Thermally isolated ground planes with a superconducting electrical coupler
Publication Date: 2022.08.03 NORTHROP GRUMMAN SYSTEMS CORP
  • EP3704739B1 patent drawingFigure 1
  • EP3704739B1 patent drawingFigure 2
  • EP3704739B1 patent drawingFigure 3~4

AI summary

An integrated circuit is provided that comprises a first ground plane associated with a first set of circuits that have a first operational temperature requirement, and a second ground plane associated with a second set of circuits that have a second operational temperature requirement that is higher than the first operational temperature requirement. The second ground plane is substantially thermally isolated from the first ground plane. A superconducting coupler electrically couples the first ground plane and the second ground plane while maintaining relative thermal isolation between the first ground plane and the second ground plane.