SQUID Diagnostic Circuit for Cryogenic CMOS Noise Immunity
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Solution Overview
Problem
Existing diagnostic circuits for monitoring CMOS circuits operating at cryogenic temperatures face challenges due to thermal noise affecting signal analysis, necessitating more accurate methods for performance monitoring.
Innovation Solution
A diagnostic circuit utilizing multiple superconducting quantum interference devices (SQUIDs) inductively coupled to an input port, each generating distinct output voltages based on threshold currents, effectively acting as an analog-to-digital converter to minimize thermal noise impact and provide accurate voltage representation of input currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If output signals are sent from cryogenic temperatures to room temperature through long wires and conditioning circuitry, then signal transmission is achieved, but thermal noise affects the signals and complicates analysis
Solution Approach 1:
The patent introduces SQUID devices as intermediary components that convert current signals to voltage signals at the cryogenic location before transmission. This mediation occurs at the source, allowing the signal to be transformed into a form that is less susceptible to thermal noise during transmission through long wires to room temperature measurement equipment.
Solution Approach 2:
The patent changes the parameter of the signal from current to voltage using SQUID devices at the cryogenic temperature location. By converting the output signal parameter before transmission, the system achieves better noise immunity and measurement precision when the signal travels through long wires to room temperature equipment.
2Measurement precision
If multiple SQUID devices are used with different threshold currents, then measurement precision and thermal noise resistance are improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement function by using multiple SQUID devices, each with a different threshold current. This segmentation allows the system to measure different current ranges with high precision by selecting the appropriate SQUID device for each measurement range, thereby improving overall measurement accuracy while managing complexity through functional division.
Solution Approach 2:
The patent creates a multi-functional measurement system where each SQUID device serves a specific measurement range. The combination of multiple SQUID devices with different thresholds provides universal current measurement capability across a wide range, allowing the system to handle various current levels with a single integrated circuit design.
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 diagnostic circuit operates with high precision, quickly responding to changes in input currents and reducing vulnerability to thermal noise, enabling accurate monitoring of CMOS circuit performance at cryogenic temperatures.
Implementation Method 1
a first superconducting quantum interference device (SQUID) inductively coupled to the input port
Data Source
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AI summary
A diagnostic circuit includes an input port configured to receive an input current and a first superconducting quantum interference device (SQUID) inductively coupled to the input port. The first SQUID is configured to generate a first output in the form of: a first voltage in response to the input current being less than a first threshold current and a second voltage in response to the input current being greater than the first threshold current. The diagnostic circuit also includes a second SQUID inductively coupled to the input port. The second SQUID is configured to generate a second output in the form of: a third voltage in response to the input current being less than a second threshold current and a fourth voltage in response to the input current being greater than the second threshold current.