Differential Microphone Independent Charge Pump Biasing

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Solution Overview

Problem

Differential microphones require separate sense-capacitors for positive and negative biasing to compensate for mechanical and electrical variations, necessitating independent adjustment of bias voltages to optimize microphone performance.

Innovation Solution

A microphone system with independently adjustable positive and negative charge pumps and sense-capacitors, along with a differential amplifier, allows for individual optimization of each sense-capacitor's bias voltage, enabling compensation for mechanical and electrical variations and maximizing signal swing and signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate sense-capacitors are used for positive and negative biasing, then mechanical and electrical variations can be compensated for, but device complexity increases

Engineering Contradiction:

Improvemicrophone performance optimizationVSAvoidnumber of sense-capacitors and biasing circuits

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the differential microphone into two independent sides, each with its own sense-capacitor and adjustable charge pump circuit. This segmentation allows each side to be independently optimized for mechanical and electrical variations, resolving the contradiction by making the system complex but functionally independent and reliable

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each sense-capacitor is provided with its own independently adjustable bias voltage through separate charge pump circuits. This local quality approach allows each component to be individually optimized according to its specific mechanical and electrical characteristics, achieving high reliability while managing complexity through modular design

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If independent adjustment of bias voltages is implemented, then each sense-capacitor can be optimized individually, but circuit complexity increases

Engineering Contradiction:

Improvebias voltage optimizationVSAvoidnumber of charge pump circuits

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements dynamically adjustable bias voltages for each sense-capacitor through charge pump circuits with adjustable control inputs. This allows the bias voltages to be optimized independently for each sense-capacitor's specific characteristics, achieving precise manufacturing optimization while using standard adjustable circuit blocks to manage complexity

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If separate charge pumps are used for positive and negative biasing, then bias voltages can be independently adjusted, but use of energy increases

Engineering Contradiction:

Improveindependent bias voltage adjustmentVSAvoidpower consumption of charge pumps

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent uses identical charge pump circuit designs for both positive and negative biasing, making each circuit multi-functional in terms of design reuse. This universality allows independent adjustment of bias voltages for adaptability while reducing overall energy consumption through standardized, optimized circuit implementations

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach enables optimal performance of differential microphones by allowing independent adjustment of bias voltages for each sense-capacitor, effectively compensating for variations and enhancing acoustic performance.

Implementation Method 1

Independent adjustment of the positive and negative biasing circuits allows for each sense-capacitor to be optimized individually

Methodology Applied

Scientific EffectCharge pump: Pump

Implementation Method 2

The positive sense-capacitor is configured to generate a positive sense voltage based on the acoustic pressure and the positive bias voltage

Methodology Applied

Scientific EffectCapacitive transduction: Capacitance

Data Source

PatentUS9602921B2Independently charge pumps for differential microphone

Publication Date: 2017.03.21 AKUSTICA INC

AI summary

Systems and methods of generating independent adjustable bias voltages for a differential microphone. The microphone system includes a positive adjustable charge pump, a positive sense capacitor, a negative adjustable charge pump, a negative sense-capacitor, and a differential amplifier. The positive adjustable charge pump is configured to generate a positive bias voltage. The positive sense-capacitor is configured to generate a positive sense voltage based on acoustic pressure from a first direction and the positive bias voltage. The negative adjustable charge pump is configured to generate a negative bias voltage. The negative sense-capacitor is configured to generate a negative sense voltage based on the acoustic pressure from the first direction and the negative bias voltage. The differential amplifier is configured to receive the positive and negative sense voltages. The differential amplifier is also configured to generate a differential voltage based on the positive and negative sense voltages.