Cryogenic Device Impedance Measurement With Path Calibration
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Solution Overview
Problem
Existing cryogenic electronic device testing systems face challenges in accurately measuring impedance characteristics due to nonidealities and transmission mismatches in the testing system, which limit the ability to precisely determine the impedance of cryogenic devices.
Innovation Solution
A cryogenic DUT testing system is configured to electrically isolate and couple a channel output circuit with a cryogenic device, using resistors along transmission paths to measure impedance characteristics by compensating for nonidealities and mismatches, and determining impedance differences to accurately calculate the impedance of the cryogenic device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a transmission path is used to couple the pattern generator circuit to the channel output circuit, then the device can operate at cryogenic temperatures, but nonidealities and transmission mismatches occur that limit measurement precision
Solution Approach 1:
The system performs preliminary characterization of the transmission path by measuring its impedance characteristics separately before using it for DUT measurements. This preliminary action allows the system to store reference data and compensate for transmission path nonidealities during actual measurements, thereby maintaining measurement precision at cryogenic temperatures
Solution Approach 2:
The channel output circuit serves as an intermediary between the pattern generator circuit and the DUT. It includes components that can be independently characterized and whose effects can be mathematically deconvolved from the total measurement, allowing accurate extraction of DUT impedance despite transmission path nonidealities
2Ease of operation
If the channel output circuit is continuously coupled to the cryogenic DUT, then the system is ready for measurement, but it becomes impossible to separate transmission path characteristics from DUT characteristics
Solution Approach 1:
The system dynamically switches between different operational states: a measurement state where the channel output circuit is coupled to the DUT, and a calibration state where it is decoupled or connected to a known reference. This dynamic reconfiguration allows the system to separately characterize transmission path and DUT properties while maintaining operational readiness
Solution Approach 2:
The measurement process is segmented into distinct phases: transmission path characterization phase and DUT measurement phase. During each phase, specific components are activated or deactivated to isolate the property being measured, allowing separate determination of transmission path and DUT impedance characteristics
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 effectively measures impedance characteristics of cryogenic devices by compensating for transmission path nonidealities and mismatches, providing accurate AC and DC impedance measurements.
Implementation Method 1
at least one resistor positioned along a transmission path that couples a pattern generator circuit to the channel output circuit
Data Source
AI summary
This disclosure relates to systems and methods for measuring impedance characteristics of a cryogenic device under test (DUT). A channel select circuit can be configured in a first state to electrically isolate a channel output circuit from the cryogenic DUT and in a second state to electrically couple the channel output circuit to the cryogenic DUT, and at least one resistor can be positioned along a transmission path that couples a pattern generator circuit to a channel output circuit that includes the channel select circuit. A controller can be configured to cause respective test current signals to be provided along the transmission path when the channel select circuit is in respective first and second states to establish respective first and second voltages across the at least one resistor, determine first and second impedance characteristics of the transmission path for determining an impedance of the cryogenic DUT.