Silicon Condenser Microphone Circuit Module PSRR Optimization
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Solution Overview
Problem
Conventional silicon condenser microphones face issues with high power consumption, low Power Supply Rejection Ratio (PSRR), and high output impedance, which affect the quality of electrical signals and overall performance.
Innovation Solution
A circuit module for silicon condenser microphones is introduced, comprising a transducer, charge pump, isolator, amplifiers, reaction circuit, and bias circuits, which includes a charge pump for providing high voltage, an isolator to isolate direct-current components, and a reaction circuit with variable capacitors to adjust sensitivity, along with low-pass filters to reduce noise and improve PSRR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional circuit design is used in silicon condenser microphone, then basic functionality is achieved, but power consumption is high and PSRR is low
Solution Approach 1:
The circuit is divided into multiple independent modules: charge pump module, isolator module, amplifier module, and reaction circuit module. Each module performs a specific function, allowing optimized power management and signal processing that reduces overall power consumption while maintaining high PSRR through modular design
Solution Approach 2:
An isolator is introduced as an intermediary component between the transducer and the amplifier. This isolator blocks direct current components and separates the high-impedance transducer from the low-impedance amplifier, enabling the system to achieve low power consumption and high PSRR by preventing signal interference and optimizing power distribution
2Reliability
If conventional circuit design is used in silicon condenser microphone, then basic functionality is achieved, but output impedance is high
Solution Approach 1:
An isolator serves as an intermediary with high input impedance and low output impedance, effectively matching the high-impedance transducer to the low-impedance amplifier. This intermediary component reduces the overall output impedance of the microphone system without requiring complex impedance matching networks
Solution Approach 2:
Different parts of the circuit are designed with different impedance characteristics optimized for their specific functions. The isolator provides high input impedance to match the transducer while providing low output impedance to drive the amplifier, creating local impedance optimization that reduces overall output impedance without excessive circuit complexity
3Object-affected harmful factors
If large air gap is designed to reduce acoustic noise, then acoustic noise is reduced, but device size increases
Solution Approach 1:
The acoustic noise is reduced by optimizing the air gap parameter within a reasonable range and compensating through circuit design. The charge pump provides enhanced bias voltage and the reaction circuit adjusts sensitivity to maintain performance with a smaller air gap, thereby reducing device size while still achieving acceptable acoustic noise levels through parameter optimization rather than simply increasing the air gap
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 results in lower power consumption, higher PSRR, and lower output impedance, enhancing the microphone's sensitivity and noise reduction capabilities.
Implementation Method 1
a movable compliant diaphragm, a rigid and fixed backplate (which together form a variable air gap capacitor)
Implementation Method 2
a charge pump for providing high voltage
Implementation Method 3
an isolator to isolate direct-current components
Implementation Method 4
low-pass filters to reduce noise and improve PSRR
Data Source
AI summary
A circuit module for a silicon condenser microphone of the present disclosure includes a transducer, a charge pump, an isolator, a first amplifier, a second amplifier, a reaction circuit, a first bias circuit, and a second bias circuit. The charge pump electrically connects to an input port of the transducer, and an output port of the transducer electrically connects to an input port of the first amplifier via the isolator. An output port of the first amplifier electrically connects to an input port of the second amplifier. The reaction circuit is arranged between the output port of the first amplifier and the input port of the transducer. The isolator isolates the direct-current components of the first electrical signal, and therefore, the oscillations of the direct-current components will not affect the performance of the first amplifier.