Class-D Audio Amplifier Feedback Circuit for Common-Mode Noise Cancellation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional class-D audio amplification circuitry struggles to effectively cancel common mode noise, leading to distortion and inefficiency, which necessitates the use of higher-performance and more costly amplifiers.

Innovation Solution

Incorporating a common mode canceller that generates an inverted pseudo output signal to cancel common mode noise in the feedback signal, allowing for the use of lower-performance amplifiers while maintaining signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional class-D audio amplification circuitry is used without a common mode canceller, then the circuit structure is simpler, but common mode noise cannot be effectively cancelled leading to signal distortion

Engineering Contradiction:

Improvesignal qualityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A common mode canceller is introduced as an intermediary component between the output stage and the summing nodes. This canceller generates an inverted pseudo output signal that acts as a mediator to counteract common mode noise in the feedback signal, thereby improving signal quality without requiring higher-performance main amplifiers

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The common mode canceller creates a copy (inverted pseudo output signal) of the output signal and uses this copy to cancel common mode noise. By generating this inverted copy and subtracting it from the feedback signal, the circuit achieves noise cancellation while maintaining the ability to use lower-performance, cost-effective amplifiers

Inventive Principle:

Principle #26Copying

2Reliability

If higher-performance amplifiers are used to handle common mode noise, then signal quality is maintained, but cost and power consumption increase

Engineering Contradiction:

Improvesignal qualityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The common mode noise cancellation function is extracted from the main amplifier and implemented as a separate common mode canceller. This allows the use of lower-performance, lower-power main amplifiers while still achieving effective noise cancellation through the dedicated canceller component

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The common mode canceller uses lower-cost, lower-performance amplifying elements specifically for the noise cancellation path. By dedicating a simpler, cheaper cancellation path to handle common mode noise, the overall system can use cost-effective components without sacrificing signal quality

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 improves noise cancellation and power efficiency, enabling the use of lower-cost amplifiers while maintaining audio signal integrity, thus enhancing the overall performance and cost-effectiveness of class-D audio amplification circuitry.

Implementation Method 1

a loop filter configured to low-pass filter the first signal to generate a filtered signal

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Implementation Method 2

a pulse width modulator configured to perform pulse width modulation on the filtered signal to generate a modulated signal

Methodology Applied

Scientific EffectPulse width modulation: Phase Modulation

Implementation Method 3

the common mode canceller being configured to generate an inverted pseudo output signal based on the differential output signal, and provide the inverted pseudo output signal to the summing nodes, the inverted pseudo output signal cancelling a common mode noise when applied to a feedback signal provided to the summing nodes

Methodology Applied

Scientific EffectSignal inversion:

Data Source

PatentUS20240154587A1Class-d audio amplification circuitry and electronic device including the same

Publication Date: 2024.05.09 SAMSUNG ELECTRONICS CO LTD

AI summary

Class-D amplification circuitry includes an operational amplifier configured to receive a differential input signal via summing nodes, and output a first signal, a loop filter configured to low-pass filter the first signal, a pulse width modulator configured to perform pulse width modulation on the filtered signal, a gate driver stage configured to generate a gate signal based on the modulated signal, an output stage configured to generate a differential output signal based on the gate signal, and a common mode canceller connected between an input node of the output stage and the summing nodes, the common mode canceller configured to generate an inverted pseudo output signal based on the differential output signal, and provide the inverted pseudo output signal the summing nodes, the inverted pseudo output signal cancelling a common mode noise when applied to a feedback signal provided to the summing nodes.