AC High Frequency Injection for DC Resistance Measurement Contact Checking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Measurement systems face issues with accurate remote sense voltage and current measurements due to high resistance or open connections in remote sense cables, leading to regulation and measurement errors, and potential equipment damage.
Innovation Solution
A system and method that injects an AC stimulus signal, such as square waves, into the sense path of a device under test to derive the effective resistance of the sense path, allowing for continuous SMU operation and analysis of harmonics to determine cable resistance without disconnecting the output voltage, thereby minimizing measurement deviations and equipment damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If remote sense measurements are performed with high resistance or open connections in sense cables, then the measurement system can operate with voltage regulation, but measurement accuracy deteriorates and equipment damage risk increases
Solution Approach 1:
The system performs a contact check measurement before the main DC resistance measurement to detect open or high-resistance connections in advance. This preliminary action identifies problematic sense cable connections before they can cause measurement errors or equipment damage, allowing the system to alert the user or adjust measurement parameters.
Solution Approach 2:
The contact check is performed periodically or automatically before each measurement sequence. This periodic verification ensures that sense cable connections remain intact throughout operation, maintaining measurement precision while preserving voltage regulation capability.
2Measurement precision
If contact check is performed by disconnecting or turning off output voltage, then sense path resistance can be measured, but continuous SMU operation is interrupted and measurement time increases
Solution Approach 1:
The contact check function is merged with the main measurement operation by superimposing a small AC test signal on top of the DC measurement signal. This allows the sense path resistance to be measured simultaneously with the voltage regulation function, eliminating the need to interrupt or disconnect the SMU output.
Solution Approach 2:
An AC test signal is introduced as an intermediary to probe the sense path resistance without disrupting the DC measurement. The AC signal rides on the DC signal, allowing separate measurement of sense cable characteristics while maintaining continuous voltage regulation and measurement operation.
3Productivity
If AC test signal is superimposed on DC stimulus signal, then contact check can be performed during measurement, but signal complexity increases
Solution Approach 1:
The system performs frequency separation or filtering to isolate the AC test signal response from the DC measurement signal. By processing the AC and DC components separately, the system can extract sense path resistance information from the AC response while maintaining the DC measurement integrity, managing signal complexity through systematic processing steps.
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
Enables accurate and precise remote sense voltage and current measurements by minimizing the impact of open or short connections and maintaining continuous SMU regulation, reducing measurement errors and equipment damage.
Implementation Method 1
A contact check circuit may superimpose a test signal over the stimulus signal to cause the DUT signal to be developed further in response to the test signal.
Implementation Method 2
The measurement instrument may receive the DUT signal over a sense path, and may derive an effective resistance of the sense path based at least in part on the DUT signal.
Data Source
AI summary
A test system may be used for obtaining accurate remote sense voltage and/or current values. A measurement instrument may provide a regulated stimulus signal to a device under test (DUT) and measure a DUT signal developed at least partially in response to the stimulus signal. A test circuit may superimpose a test signal over the stimulus signal to cause the DUT signal to be developed further in response to the test signal. The DUT signal may be used to derive a resistance of the path that couples the measurement instrument to the DUT. The measurement instrument may include a source measure unit, the stimulus signal may be a regulated voltage, and the DUT signal may be a sense voltage. The harmonics of the DUT signal may be analyzed to determine a correlation between an amplitude of a measured fundamental frequency of the DUT signal and the resistance of the path.