V2V Sense Electrode Feedback to Minimize Sensor Spring Softening
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Solution Overview
Problem
Conventional electromechanical sensors are susceptible to changes in sensitivity due to die stress, assembly variations, and operating conditions, leading to 'spring softening' effects that alter the resonant frequency and gain of the sensor elements, which is exacerbated by charge-to-voltage architectures maintaining constant voltage across capacitive sense elements.
Innovation Solution
The application of a positive feedback voltage using a voltage-to-voltage converter, coupled via a defined feedback capacitance to maintain a constant charge at the sense electrode, effectively reducing the sensitivity of the sensor elements and minimizing the spring softening effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a charge-to-voltage (C2V) architecture is used to maintain a constant voltage across the sense gap, then the voltage stability is improved, but the spring softening effect is worsened
Solution Approach 1:
The patent inverts the conventional C2V architecture by implementing a voltage-to-voltage (V2V) converter that maintains constant voltage at the sense node through virtual grounding, rather than maintaining constant voltage across the sense gap. This inversion eliminates the spring softening effect while achieving voltage stability through a different mechanism.
Solution Approach 2:
The patent changes the control parameter from constant voltage across sense gap (C2V) to constant voltage at sense node (V2V). By changing which voltage parameter is held constant and how it is achieved, the system eliminates spring softening while maintaining voltage stability through virtual grounding at the sense node.
2Device complexity
If conventional sensor technologies are used, then the device complexity is reduced, but the sensitivity variations due to die stress and assembly variations are worsened
Solution Approach 1:
The patent implements a feedback mechanism through the V2V converter that continuously monitors and maintains constant voltage at the sense node. This feedback loop compensates for sensitivity variations caused by die stress and assembly variations, improving measurement precision while managing device complexity through integrated circuit implementation.
3Stability of the object's composition
If a C2V architecture is used, then the voltage across sense gap is stabilized, but the charge flow representing spring softening is increased
Solution Approach 1:
The patent extracts the problematic charge flow through the sense capacitor by implementing virtual grounding at the sense node. By removing the charge accumulation that represents spring softening and redirecting it through the V2V converter's feedback path, the system stabilizes voltage while eliminating excessive charge flow.
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 significantly reduces the sensitivity variations of electromechanical sensors, such as gyroscopes and accelerometers, by maintaining a constant charge at the sense electrodes, thereby eliminating the spring softening effect and stabilizing the mechanical-to-electrical gain, with a reduction of over 95% in charge changes due to parasitic capacitance.
Implementation Method 1
applying a positive feedback voltage using a voltage-to-voltage converter, coupled via a defined feedback capacitance to maintain a constant charge at the sense electrode
Implementation Method 2
coupled via a defined feedback capacitance to maintain a constant charge at the sense electrode
Data Source
AI summary
Reducing a sensitivity of an electromechanical sensor is presented herein. The electromechanical sensor comprises a sensitivity with respect to a variation of a mechanical-to-electrical gain of a sense element of the electromechanical sensor; and a voltage-to-voltage converter component that minimizes the sensitivity by coupling, via a defined feedback capacitance, a positive feedback voltage to a sense electrode of the sense element—the sense element electrically coupled to an input of the voltage-to-voltage converter component. In one example, the voltage-to-voltage converter component minimizes the sensitivity by maintaining, via the defined feedback capacitance, a constant charge at the sense electrode. In another example, the electromechanical sensor comprises a capacitive sense element comprising a first node comprising the sense electrode. Further, a bias voltage component can apply a bias voltage to a second node of the electromechanical sensor. In yet another example, the electromechanical sensor comprises a piezoelectric sense element.