Spatially Distributed Guarded Impedance for Precision Measurement
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Solution Overview
Problem
Precision electrical measurements, especially in pulsed and RF circuits, face challenges in minimizing noise leakage and stray impedance effects due to the increasing need for faster and more precise measurements, which existing guarding techniques struggle to address effectively.
Innovation Solution
The implementation of a guarded sense impedance with spatially distributed electrical potential and guard structures, such as serpentine resistances, interdigitating electrode pairs, or arrays of guard electrodes, that match the potential gradients of the sense impedance, providing effective shielding from leakage and stray impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional guarding techniques are used, then measurement precision is improved, but measurement speed deteriorates due to the need to allow transients to subside between measurements
Solution Approach 1:
The guard structure is segmented into multiple discrete electrodes arranged in an array along the sense impedance. Each guard electrode can be independently controlled to provide localized guarding at different positions, allowing faster transient settling while maintaining precision measurement capabilities.
Solution Approach 2:
The guarding technique transitions from static DC potential to dynamic time-varying potential that follows the signal waveform. The guard electrodes are driven by buffered versions of the signal waveform, enabling the guard potential to adapt dynamically to changing signal conditions and allow faster measurements without sacrificing precision.
2Object-affected harmful factors
If traditional guarding techniques are used, then noise leakage is minimized, but the technique fails to effectively address pulsed and RF circuit measurements
Solution Approach 1:
The guard potential changes from constant DC level to time-varying waveform that matches the signal characteristics. This parameter change enables effective guarding across different frequency ranges including pulsed and RF measurements, while continuing to minimize noise leakage through the same fundamental guarding mechanism.
Solution Approach 2:
The time-varying guard technique provides universal applicability across multiple measurement types (DC, pulsed, RF) by adapting the guard potential waveform to match the signal being measured. A single guarding system can handle diverse measurement scenarios by changing the temporal characteristics of the guard potential.
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
This approach enhances measurement precision and bandwidth by isolating the sense impedance from noise, allowing for more accurate and faster measurements by matching the spatially distributed potential of the guard structures with the sense impedance, thereby reducing leakage and stray impedance effects.
Implementation Method 1
A guarded sense impedance for use in a measurement instrument includes a sense impedance adapted to have a spatially distributed electrical potential and at least one guard structure adapted to have the spatially distributed electrical potential
Data Source
AI summary
A guarded sense impedance for use in a measurement instrument includes a sense impedance adapted to have a spatially distributed electrical potential and at least one guard structure adapted to have the spatially distributed electrical potential. The guard structure is arranged to provide a spatially distributed guard potential for the sense impedance.