Glitch Detection Circuit for Electret Microphone Sensitivity Calibration
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Solution Overview
Problem
Achieving high sound quality in low-cost electret condenser microphones is challenging due to their complex manufacturing process and sensitivity issues, which affect their performance in consumer applications like cellular telephones and digital audio recorders.
Innovation Solution
A glitch detection circuit that increases the bias voltage of a capacitor, samples the input signal, mixes it with a sampled signal, and compares it to a reference signal to detect glitches, integrated within the microphone system for calibration and normal operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple discrete parts are used in ECM microphone manufacturing, then the microphone can be produced at low cost, but manufacturing precision and sound quality deteriorate due to complex manufacturing processes and sensitivity variations
Solution Approach 1:
The patent applies preliminary action by performing glitch detection and calibration before the microphone is finalized for production. The detection circuit identifies sensitivity variations and manufacturing defects early in the process, allowing corrections to be made before the product reaches the customer, thus improving consistency without requiring complete redesign of the manufacturing process
Solution Approach 2:
The patent implements feedback through a detection circuit that measures microphone sensitivity and provides information about manufacturing variations. This feedback loop allows the system to identify and compensate for sensitivity variations, improving manufacturing precision while maintaining the cost-effective discrete parts approach
2Reliability
If glitch detection circuit is added to the microphone system, then sound quality and sensitivity are improved, but device complexity increases
Solution Approach 1:
The patent merges the glitch detection circuit with the existing microphone structure, integrating the detection functionality into the overall microphone system rather than adding completely separate components. This reduces the overall device complexity while still providing the necessary sound quality improvements
Solution Approach 2:
The detection circuit is designed to perform multiple functions including glitch detection, sensitivity measurement, and calibration operations. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving reliability improvements
Data Source
AI summary
System and method for detecting a glitch is disclosed. An embodiment comprises increasing a bias voltage of a first capacitor, sampling an input signal of a first plate of the first capacitor with a time period, mixing the input signal with the sampled input signal, and comparing the mixed signal with a reference signal.