Scalar Physical Quantity Measuring Unit With Dual Feedback Loops
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Solution Overview
Problem
Existing measuring units for scalar physical quantities and their gradients face challenges in achieving high sensitivity, large bandwidth, and accurate measurement of very low frequency fields without disturbing the physical quantity being measured, especially in applications where electrical contact is not possible or desirable.
Innovation Solution
A novel measuring unit design featuring a pair of sensactors with fully differential amplifier means and multi-source, multi-loop feedback processes, allowing simultaneous processing of common and differential modes, which enhances bandwidth, dynamic range, and linearity, and enables measurement of scalar physical quantities and their gradients without electrical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional feedback theory with single feedback loop is used, then linearity and dynamic range are improved, but bandwidth is limited and common mode signals cannot be processed
Solution Approach 1:
The patent divides the feedback system into two independent feedback loops: a first feedback loop for processing differential mode signals and a second feedback loop for processing common mode signals. This segmentation allows each loop to be optimized independently, enabling the system to achieve both high linearity through the differential loop and extended bandwidth through the common mode loop simultaneously.
Solution Approach 2:
The patent transitions from conventional single-loop feedback to a two-dimensional feedback architecture by adding the common mode feedback loop as an additional dimension. This allows the system to process both differential and common mode signals concurrently, effectively expanding the operational bandwidth while maintaining measurement precision through the original differential feedback path.
2Measurement precision
If electrical contacts are made for measurement, then sensitivity is improved, but the measured physical quantity is disturbed
Solution Approach 1:
The patent introduces sensing electrodes that function as intermediaries between the measurement system and the physical quantity being measured. These electrodes detect electric fields and potentials without requiring direct electrical contact with the source, thereby maintaining high sensitivity through electromagnetic coupling while avoiding disturbance that would result from physical contact.
Solution Approach 2:
The patent replaces conventional electrical contact-based measurement mechanisms with field-based sensing. By using sensing electrodes to detect electric fields and potentials through electromagnetic interaction rather than direct electrical connection, the system achieves high sensitivity without the mechanical/electrical contact that would disturb the measured quantity.
3Measurement precision
If differential amplification is used, then signal difference detection is improved, but common mode amplification becomes problematic
Solution Approach 1:
The patent segments the signal processing function into two independent pathways: a differential amplification path for detecting signal differences and a separate common mode feedback path for stabilizing common mode amplification. This segmentation allows the differential path to focus on precise difference detection while the common mode path independently manages amplification stability, preventing interference between the two functions.
Solution Approach 2:
The patent implements a dedicated common mode feedback loop that actively monitors and stabilizes the common mode signal level. This feedback mechanism compensates for variations in common mode amplification, ensuring reliability and stability while allowing the differential amplification path to maintain high precision in signal difference detection.
Data Source
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AI summary
The invention relates to a physical quantity measuring unit, in particular a scalar physical measuring unit providing the scalar quantity and its gradient, comprising: a sensing means comprising a first and a second sensactor, wherein the first sensactor is configured to provide a first output and comprises a first and second feedback input and the second sensactor is configured to provide a second output and comprises a third and fourth feedback input, a fully differential amplifier means comprising differential outputs and a common mode output, wherein the first and second output of the sensing means is connected to a first input and a second input of the fully differential amplifier means respectively, two feedback loops connecting the differential outputs of the fully differential amplifier means to the first and third feedback inputs with a signal sign inversion, and a third feedback loop connecting the common mode output of the fully differential amplifier means with the second and fourth feedback inputs of the sensing means.