Variable Bandwidth DC Bias Loop for AC Measurement Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing closed-loop measurement systems face challenges in integrating DC and AC measurements on a device under test (DUT) due to conflicts between DC and AC feedback loops, particularly when rapid bias changes are needed, leading to increased settling times and reduced measurement throughput.
Innovation Solution
A method involving a variable bandwidth DC bias loop and an AC measurement loop, where the AC loop is disabled and the DC loop is set to high bandwidth for rapid DC bias changes, and vice versa for AC measurements, allowing for efficient handling of fast DC steps without compromising AC measurement capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the DC bias loop operates at high bandwidth to establish rapid DC bias changes, then the settling time is reduced and measurement throughput is improved, but the AC measurement loop conflicts with the DC bias loop causing measurement accuracy to deteriorate
Solution Approach 1:
The patent applies dynamics by making the DC bias loop bandwidth variable rather than fixed. The system dynamically adjusts the DC loop bandwidth based on operational mode: high bandwidth during DC bias establishment phase for fast settling, and low bandwidth during AC measurement phase for high precision. This temporal variation in system parameters resolves the contradiction between speed and accuracy.
Solution Approach 2:
The system employs periodic action through sequential operation phases. The DC bias loop operates at high bandwidth during DC establishment phases, then transitions to low bandwidth during AC measurement phases. This periodic switching between operational modes allows the system to achieve both fast settling and accurate measurements at different times without conflict.
2Measurement precision
If the AC measurement loop is enabled for accurate AC measurements, then measurement precision is improved, but the DC bias loop settling time increases due to loop conflicts
Solution Approach 1:
The system dynamically adjusts the DC loop bandwidth based on operational requirements. When AC measurements are needed, the DC loop bandwidth is reduced to prevent conflicts, allowing the AC measurement loop to operate with high precision without interference. This adaptive bandwidth adjustment resolves the trade-off between measurement accuracy and settling time.
Solution Approach 2:
The system performs preliminary DC bias establishment at high bandwidth before transitioning to AC measurement mode. By completing the DC bias setup phase first with high-speed response, then switching to low-bandwidth DC loop for AC measurements, the system ensures both fast initial settling and accurate subsequent measurements without mutual interference.
3Adaptability or versatility
If DC and AC measurements are integrated on the same system, then device versatility is improved, but loop conflicts increase causing system complexity to worsen
Solution Approach 1:
The system manages the complexity of integrated DC and AC measurements through dynamic bandwidth adjustment of the DC loop. By automatically switching between high and low bandwidth modes based on the active measurement type, the system provides versatile integrated functionality while keeping the control logic manageable through well-defined operational phases and mode transitions.
Data Source
AI summary
A method for controlling a measurement system includes providing a variable bandwidth DC bias loop for biasing a DUT; providing an AC measurement loop for measuring AC parameters of the DUT; disabling the AC measurement loop and selecting a high bandwidth for the DC bias loop when rapid changes to the DC bias are to be made; and selecting a low bandwidth for said DC bias loop and enabling the AC measurement loop when AC measurements of the DUT are to be made.