Digital Microphone Input Circuit High-Frequency Interference Rejection
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Solution Overview
Problem
Existing digital microphones suffer from poor anti-high-frequency interference capabilities and low high-frequency power supply rejection ratio due to high-frequency interference signals in analog electronic signals and power supply, which affect the performance of processing chips in portable devices.
Innovation Solution
Incorporating a PMOS transistor with specific branch configurations, a resistor, a current source, and a low-pass filter in the input circuit of the processing chip, where the low-pass filter connects to the amplifier circuit, effectively filtering out high-frequency interference signals and improving the chip's anti-high-frequency interference capabilities and power supply rejection ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional input circuit design is used, then device simplicity is maintained, but anti-high-frequency interference capabilities are poor
Solution Approach 1:
The patent introduces a low-pass filter as an intermediary component between the microphone and amplifier circuit. This filter acts as a mediator that selectively passes low-frequency signals while blocking high-frequency interference, thereby improving anti-interference capabilities without requiring complete redesign of the input circuit architecture.
Solution Approach 2:
The input circuit is segmented into distinct functional modules: a PMOS transistor for signal reception, a low-pass filter for frequency selection, and an amplifier circuit for signal enhancement. This segmentation allows each component to perform its specific function optimally, improving overall reliability while maintaining manageable complexity through modular design.
2Reliability
If conventional power supply design is used, then power supply simplicity is maintained, but high-frequency power supply rejection ratio is low
Solution Approach 1:
The low-pass filter serves as a power supply rejection mechanism by filtering out high-frequency noise from the power supply line. It acts as an intermediary that allows DC and low-frequency power components to pass while blocking high-frequency interference, thereby improving power supply rejection ratio without complex power management circuits.
3Reliability
If signal amplification is performed without filtering, then signal processing simplicity is maintained, but high-frequency interference is amplified along with the signal
Solution Approach 1:
The low-pass filter is placed before the amplifier circuit to perform preliminary filtering of the signal. By removing high-frequency interference components before amplification, the filter prevents these unwanted signals from being amplified along with the desired signal, thereby improving signal quality while keeping the processing circuit relatively simple.
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 described configuration enhances the processing chip's ability to reject high-frequency interference, improving its anti-high-frequency interference capabilities and increasing the high-frequency power supply rejection ratio, leading to better performance in digital microphones.
Implementation Method 1
A low-pass filter, wherein one end of the low-pass filter is configured to connect to the third branch of the source of the PMOS transistor and the other end of the low-pass filter is configured to connect to an amplifier circuit
Data Source
AI summary
A processing chip for a digital microphone and related input circuit and a digital microphone are described herein. In one aspect, the input circuit for a processing chip of a digital microphone includes: a PMOS transistor, a resistor, a current source, and a low-pass filter. The described processing chip possesses high anti high-frequency interference capabilities and the described input circuit possesses high high-frequency power supply rejection ratio.