Compound SQUID Output Amplifier for SFQ-to-NRZ Conversion

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Solution Overview

Problem

CMOS-based digital circuits face limitations in device size and high power consumption due to leakage current, even when inactive, leading to significant energy wastage in devices like servers in data centers.

Innovation Solution

The implementation of a superconducting logic-based output amplifier system using compound superconducting quantum interference devices (SQUIDs) that convert single flux quantum pulses into non-return-to-zero (NRZ) voltage waveforms, utilizing Josephson junctions and inductors to minimize power dissipation and leverage AC power for efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If CMOS technology is used for digital circuits, then device integration is achieved, but power consumption increases due to leakage current even when circuits are inactive

Engineering Contradiction:

Improvedevice integrationVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent transitions from CMOS technology operating at room temperature to superconducting technology operating at cryogenic temperatures (near absolute zero). This parameter change in temperature enables superconducting circuits to achieve zero resistance and eliminate leakage current, thereby resolving the contradiction between device integration and power consumption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the CMOS electronic system with a superconducting quantum interference device (SQUID) based system. This substitution uses Josephson junctions and magnetic flux quantization principles to create logic circuits that operate without resistive losses, eliminating the leakage current problem inherent in CMOS technology while maintaining computational functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If CMOS circuits are kept inactive to save power, then dynamic power consumption decreases, but static power is still consumed to maintain transistor states

Engineering Contradiction:

Improvedynamic power consumptionVSAvoidstatic power consumption

Core Design Contradiction:

Loss of energyVSUse of energy by stationary object

Solution Approach 1:

By changing the operating temperature parameter to cryogenic levels, the patent enables superconducting materials to exhibit zero electrical resistance. This eliminates both dynamic and static power consumption in superconducting circuits, as no energy is required to maintain the logical state of superconducting elements, unlike CMOS transistors that require continuous power to maintain their state.

Inventive Principle:

Principle #35Parameter changes

3Area of moving object

If device size is reduced to increase integration, then circuit density improves, but leakage current increases leading to higher power consumption

Engineering Contradiction:

Improvedevice sizeVSAvoidleakage current

Core Design Contradiction:

Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent replaces CMOS-based miniaturized circuits with superconducting SQUID circuits. The superconducting logic elements use macroscopic quantum phenomena (Josephson effect, magnetic flux quantization) that are not subject to the same leakage current mechanisms as CMOS transistors. This substitution allows for high-density integration without the leakage current penalty that plagues scaled CMOS devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces static power dissipation and enables efficient power management by converting SFQ pulses into NRZ voltage waveforms, potentially lowering energy consumption in data center servers and other electronic devices.

Implementation Method 1

a first Josephson junction coupled between the first terminal and the third terminal. The output amplifier stage may further include a second inductor coupled between the second terminal and a fourth terminal. The output amplifier stage may further include a second Josephson junction coupled between the second terminal and the fourth terminal.

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

a compound superconducting quantum interference device (SQUID) configured to convert the first pulse train and the second pulse train into a non-return-to-zero (NRZ) voltage waveform

Methodology Applied

Scientific EffectSuperconducting quantum interference: Superconductivity

Data Source

PatentUS10651808B2Compound superconducting quantum interference device output amplifier and methods

Publication Date: 2020.05.12 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Output amplifier comprising a stack of compound superconducting quantum interference device (SQUID) output amplifier stages and related methods are provided. A method includes receiving a first pulse train comprising a first plurality of single flux quantum (SFQ) pulses. The method may further include receiving a second pulse train comprising a second plurality of SFQ pulses, where the second pulse train is delayed by a predetermined fraction of a clock cycle relative to the first pulse train. The method may further include using the stack of the plurality of compound SQUID output amplifier stages converting the first plurality of SFQ pulses and the second plurality of SFQ pulses into a voltage waveform, where each of the plurality of compound SQUID output amplifier stages comprises a pair of superconducting quantum interference devices (SQUIDs).