MEMS Microphone Acoustic Overload and ESD Protection via Inverted Biasing
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Solution Overview
Problem
Microphones, particularly MEMS microphones, face issues with acoustic overload and electrostatic discharge, which can damage the device and degrade its performance due to the high bias voltage applied to the backplate and the low capacitive source of the diaphragm, leading to increased capacitive loading and reduced signal-to-noise ratio.
Innovation Solution
A system comprising a sensor component with a backplate and diaphragm biased to specific voltage levels, utilizing feedback circuitry to generate an inverted signal that is fed back to the backplate, enhancing the acoustic overload point and incorporating electrostatic discharge protection by biasing the backplate to a low voltage level, thereby mitigating the effects of electrostatic discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the backplate is biased to a high DC voltage to facilitate microphone operation, then the microphone can operate properly, but the acoustic overload point is reduced and the device becomes vulnerable to electrostatic discharge damage
Solution Approach 1:
The patent inverts the conventional biasing approach by biasing the backplate to ground or a low voltage level instead of a high voltage level, while biasing the diaphragm to a high voltage level. This inversion resolves the contradiction by providing electrostatic discharge protection to the backplate while maintaining proper microphone operation through the high voltage on the diaphragm.
Solution Approach 2:
The patent changes the voltage level parameters of the biasing circuitry. Specifically, it modifies the backplate bias voltage from a high level (e.g., 12 volts) to a low level (ground or near ground), and adjusts the diaphragm bias voltage accordingly to maintain the necessary voltage differential for proper microphone operation.
2Measurement precision
If the diaphragm is biased to ground with high impedance to allow signal generation, then the diaphragm can generate electrical signals, but the capacitive loading increases and signal-to-noise ratio decreases
Solution Approach 1:
The patent changes the voltage level parameter of the diaphragm bias from ground to a high voltage level. This parameter change reduces the capacitive loading effect and improves the signal-to-noise ratio while maintaining proper signal generation capability.
3Object-affected harmful factors
If feedback circuitry is added to generate inverted signal to enhance acoustic overload point, then the acoustic overload point is doubled, but the device complexity increases
Solution Approach 1:
The patent implements feedback circuitry that receives the signal from the diaphragm and generates an inverted signal that is supplied to the backplate. This feedback mechanism enhances the acoustic overload point by doubling it, providing a systematic solution to protect against acoustic overload while maintaining manageable circuit complexity.
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
The solution effectively doubles the acoustic overload point and provides robust electrostatic discharge protection, maintaining sensitivity and reducing the impact of high acoustic overload situations while simplifying biasing and reducing light exposure sensitivity.
Implementation Method 1
employing feedback circuitry to facilitate enhancing an acoustic overload point of a sensor component... a feedback component that receives the signal from the diaphragm component and generates an inverted signal... wherein the inverted signal or a processed inverted signal that is based at least in part on the inverted signal is transmitted to the backplate component
Implementation Method 2
a sensor component that senses an input signal, wherein the sensor component comprises a backplate component, and a diaphragm component that generates a signal based at least in part on movement of the diaphragm component in relation to the backplate component
Data Source
AI summary
A feedback signal is employed to facilitate enhancing an acoustic overload point and electrostatic discharge protection of a sensor component and associated circuit. The sensor component comprises a backplate component and a diaphragm component. The backplate component is biased to a low-level voltage associated with a ground. The diaphragm component is biased to a defined high-voltage associated with a charge pump. The diaphragm component generates a signal based on movement of the diaphragm component in relation to the backplate component in response to the input signal. A feedback component receives the signal from the diaphragm component and generates an inverted signal based on the signal. The inverted signal or a processed inverted signal, which can be derived from a filter component that filters the inverted signal, is transmitted to the backplate component.