Microphone Circuit Mode Switching and EMI Reduction
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Solution Overview
Problem
Existing microphone electronic circuits face challenges in efficiently operating in both two-terminal and three-terminal modes, requiring separate terminals for power, output, and ground, and struggle with electromagnetic interference and sensitivity variations due to external components.
Innovation Solution
An electronic circuit configured as an ASIC with a programmable non-volatile memory and switchable resistors allows operation in both two-terminal and three-terminal modes, providing EMI protection and adjustable sensitivity by integrating resistors and controlling them via memory, enabling the same circuit to be used in both modes with reduced space and sensitivity variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate terminals are provided for power, ground and output (three-terminal mode), then the microphone can operate with dedicated functions for each terminal, but the device complexity increases and space is consumed
Solution Approach 1:
The second terminal is designed to perform multiple functions depending on the operating mode: it can serve as ground in two-terminal mode or as microphone output in three-terminal mode. This multi-functionality allows the same physical terminal to replace what would traditionally require separate dedicated terminals, reducing device complexity while maintaining functional reliability through mode selection
2Measurement precision
If external resistors are used for sensitivity adjustment, then the sensitivity can be tuned, but the manufacturing precision decreases due to tolerance variations
Solution Approach 1:
The resistor that was previously an external component is merged into the integrated circuit itself. This integration eliminates the need for external resistors with tolerances, as the resistive elements are now part of the manufactured IC where their values are precisely controlled during the semiconductor fabrication process, thereby improving manufacturing precision while retaining sensitivity adjustment capability
Solution Approach 2:
The mechanical adjustment of external resistors is replaced by electronic control within the IC. The memory-controlled switches electronically select different resistor configurations or values, replacing the need for physical external components and their associated tolerance variations, thus improving manufacturing precision
3Device complexity
If the electronic circuit is designed for a specific mode only, then the design is simpler, but the adaptability decreases
Solution Approach 1:
The electronic circuit incorporates dynamic reconfiguration capability through memory-controlled switches that can change the circuit's connectivity and configuration based on the selected operating mode. This dynamic switching allows the same circuit design to adapt to different operational requirements (two-terminal or three-terminal mode) without requiring separate dedicated designs for each mode, thereby improving adaptability while managing complexity through systematic control
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 enables flexible operation in different modes with reduced sensitivity variation and electromagnetic interference, improving the microphone's performance and efficiency by integrating resistors and using memory-controlled switches to adjust sensitivity and current consumption.
Implementation Method 1
A capacitor may be provided to connect the second terminal capacitive to ground. Additionally, electromagnetic interference (EMI) protection may be provided by the capacitor.
Implementation Method 2
The electronic circuit may comprise an adjustable load. In particular, the electronic circuit may comprise at least one switchable resistor. The switchable resistor allows adjusting the sensitivity of the electronic circuit resp. of the microphone to the target.
Implementation Method 3
The microphone may be fabricated in MEMS technology (micro-electrical-mechanical systems).
Data Source
AI summary
An electronic circuit for a microphone comprises a first terminal and a second terminal, wherein the electronic circuit is selectively operable in a first mode and a second mode. In the first mode, the first terminal is configured for microphone output and in the second mode, the second terminal is configured for microphone output. Furthermore, a method of operating a microphone is provided.