Source Measure Circuit for Sensing Path Overvoltage Detection
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Solution Overview
Problem
Existing source measure units (SMUs) face issues with overvoltage damage to devices under test (DUTs) due to disconnection of sensing paths, leading to invalid measure voltages and malfunctioning abnormality detection circuits when conditions like incorrect overlapping or vibration occur.
Innovation Solution
A source measure device equipped with a current and voltage sampling circuit, an overvoltage detecting circuit, and a comparing circuit that generates a detection voltage based on operation voltages from these circuits, allowing for accurate abnormality determination even when the voltage sampling circuit is disconnected, and includes a control circuit to stop outputting voltage to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a four-wire type sensing path is used to measure voltage, then measurement accuracy is improved, but the system becomes vulnerable to disconnection caused by incorrect overlapping or vibration, leading to overvoltage damage
Solution Approach 1:
The patent performs preliminary actions by establishing multiple monitoring mechanisms before disconnection occurs. The overvoltage detecting circuit continuously monitors the sensing path status, and the comparing circuit pre-establishes safe voltage ranges. When disconnection occurs, these pre-established monitoring mechanisms immediately detect the abnormality and trigger protection, preventing overvoltage damage before it can occur.
Solution Approach 2:
The patent implements feedback through the overvoltage detecting circuit that continuously monitors the voltage across the sensing path and feeds this information back to the comparing circuit. The comparing circuit compares the monitored voltage against pre-set safe ranges and generates abnormality signals when deviations are detected. This closed-loop feedback system enables real-time detection and response to sensing path disconnection, maintaining system reliability while preserving measurement accuracy.
2Difficulty of detecting and measuring
If the voltage sampling circuit is used for abnormality detection, then detection capability is improved, but the circuit fails to operate when the sensing path is disconnected
Solution Approach 1:
The patent segments the detection function into independent components: the voltage sampling circuit for normal operation, the overvoltage detecting circuit for continuous monitoring, and the comparing circuit for abnormality determination. This segmentation allows the overvoltage detecting circuit to function independently of the voltage sampling circuit's connection status. When disconnection occurs, the overvoltage detecting circuit continues to monitor through alternative paths, ensuring the abnormality detection capability remains reliable and stable.
Solution Approach 2:
The overvoltage detecting circuit acts as an intermediary between the sensing path and the comparing circuit. It receives voltage signals from both the current sampling circuit and voltage sampling circuit, processes them through independent monitoring, and generates detection voltages for comparison. This intermediary function ensures that the abnormality detection circuit can operate reliably even when the voltage sampling circuit is disconnected, as the overvoltage detecting circuit uses alternative signal paths to maintain detection capability.
3Measurement precision
If the sensing path is disconnected due to vibration or incorrect overlapping, then the measure voltage becomes invalid, but the system enters open circuit state causing overvoltage damage
Solution Approach 1:
The patent performs preliminary protection actions by pre-establishing overvoltage detection thresholds and monitoring mechanisms before disconnection occurs. The overvoltage detecting circuit continuously monitors the sensing path status and the comparing circuit pre-sets safe voltage ranges. When disconnection occurs and the system enters open circuit state, these pre-established protection mechanisms immediately detect the abnormality and trigger control signals to prevent overvoltage damage to the DUT, acting before the harmful effect can occur.
Solution Approach 2:
The patent implements feedback protection through the overvoltage detecting circuit that continuously monitors voltage levels and feeds this information back to the comparing circuit. The comparing circuit compares monitored voltages against pre-set safe ranges and generates abnormality signals when deviations are detected. This feedback mechanism enables real-time detection of sensing path disconnection and immediate response to prevent overvoltage damage, maintaining measurement validity while protecting the DUT from harmful effects.
Data Source
AI summary
A source measure device includes a current sampling circuit, a voltage sampling circuit, an overvoltage detecting circuit, and a comparing circuit. The current sampling circuit is configured to sample a current of a device under test. The voltage sampling circuit is configured to sample a voltage of the device under test. The overvoltage detecting circuit is coupled to the current sampling circuit and the voltage sampling circuit, and receives a first operation voltage of the current sampling circuit and a second operation voltage of the voltage sampling circuit so as to generate a detection voltage. The comparing circuit is coupled to the overvoltage detecting circuit, and determines whether the detection voltage is within a voltage range. If the detection voltage is not within the voltage range, the comparing circuit generates an abnormal signal.