Threshold-Switched Microphone Bias Circuit for Overload
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Solution Overview
Problem
Existing microphone circuits fail to effectively raise the sound pressure overload point and maintain good electrical performance, leading to issues with total harmonic distortion and output signal quality.
Innovation Solution
A microphone circuit with a bias network module that includes a series of threshold voltage groups and corresponding impeders to reduce vibration amplitude when signal voltage exceeds a preset range, using PMOS and NMOS tubes and impeders to manage load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the microphone circuit uses a simple amplifier and resistor configuration, then the device complexity is low, but the sound pressure overload point cannot be effectively raised and total harmonic distortion performance deteriorates
Solution Approach 1:
The bias network module is divided into multiple parallel circuits, each with different threshold voltages and impeders. This segmentation allows the system to handle different signal amplitude ranges separately, effectively raising the sound pressure overload point without requiring a completely complex circuit redesign.
Solution Approach 2:
The bias network module dynamically switches between different impeder configurations based on the input signal voltage level. When the signal exceeds the threshold voltage, the corresponding impeder is connected to reduce the equivalent load resistance and attenuate the signal, preventing overload while maintaining circuit simplicity.
2Reliability
If the microphone circuit uses a fixed load resistance configuration, then the device complexity is low, but the output signal quality deteriorates when signal voltage exceeds the power supply clamping range
Solution Approach 1:
The bias network module monitors the input signal voltage and provides feedback control. When the signal voltage exceeds the threshold, the system automatically connects the appropriate impeder to adjust the load resistance, ensuring the output signal remains within the acceptable range defined by the power supply and grounding clamping levels.
Solution Approach 2:
The circuit changes the load resistance parameter dynamically based on the signal conditions. By switching between different impeder configurations, the equivalent load resistance is adjusted to match the signal amplitude, maintaining output signal quality without requiring a completely complex active control system.
3Reliability
If the microphone circuit does not include signal amplitude control, then the device complexity is low, but total harmonic distortion increases when vibration amplitude exceeds the preset range
Solution Approach 1:
The bias network module is configured in advance with multiple threshold voltages and corresponding impeders. Before the signal exceeds the overload point, the system is already prepared with the appropriate attenuation mechanisms in place, allowing it to immediately respond and maintain low total harmonic distortion when the signal amplitude increases.
Data Source
AI summary
The invention provides a microphone circuit, which includes an amplifier, a bias resistor and a bias network module. The first terminal of bias resistor connects to the preset bias voltage. The second end of the bias resistor connects the output end of the microphone. The bias network module is used to judge level of the voltage value of the signal. If the voltage value of the signal exceeds the preset voltage value of the threshold voltage group range, connect the impeder corresponding to the bias network module to the input end of the microphone circuit. The invention provides a microphone module and a method for raising sound pressure overload point of microphone. Compared with the related art, the technical scheme of the invention improves the sound pressure overload point of microphone and has good electrical performance.