Audio Amplifier Filter Topology With Fewer Op-Amps

Solution Overview

Problem

Existing audio amplifying circuits face issues with large circuit area occupation and high power consumption due to the use of multiple operational amplifiers, leading to harmonic interference and reduced signal linearity.

Innovation Solution

The proposed audio amplifying circuit reduces the number of operational amplifiers in N-order filters while maintaining filtering effectiveness, utilizing integrated circuits and optional weighting adders to improve signal linearity and reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple operational amplifiers are used in N-order filters, then filtering effect is improved, but circuit area and power consumption increase

Engineering Contradiction:

Improvefiltering effectVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple filter stages into a single N-order filter structure that uses fewer operational amplifiers than the traditional approach of using N separate first-order filters. This merging reduces the total number of operational amplifiers required while maintaining the N-order filtering effect, thereby reducing circuit area and power consumption.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent designs a universal N-order filter structure that can perform high-order filtering functions with fewer operational amplifiers. This multi-functional structure allows a single circuit block to replace multiple separate filter stages, achieving both area reduction and maintained filtering performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple operational amplifiers are used in N-order filters, then filtering effect is improved, but power consumption increases

Engineering Contradiction:

Improvefiltering effectVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent combines multiple filter stages into a single N-order filter structure that uses fewer operational amplifiers than the traditional approach of using N separate first-order filters. This merging reduces the total number of operational amplifiers required while maintaining the N-order filtering effect, thereby reducing circuit area and power consumption.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the architectural parameters of the filter from multiple first-order filters to a consolidated N-order filter structure. This parameter change in the filter order configuration reduces the number of active components (operational amplifiers) while maintaining the same filtering performance, thus reducing power consumption.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multiple operational amplifiers are used, then filtering capability is enhanced, but signal linearity deteriorates due to harmonic interference

Engineering Contradiction:

Improvefiltering capabilityVSAvoidharmonic interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent combines multiple filter stages into a single N-order filter structure that uses fewer operational amplifiers than the traditional approach of using N separate first-order filters. This merging reduces the total number of operational amplifiers required while maintaining the N-order filtering effect, thereby reducing circuit area and power consumption.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12451849B2Audio amplifying circuit and playing device

Publication Date: 2025.10.21 RDA MICROELECTRONICS SHANGHAICO LTD

AI summary

The present disclosure provides an audio amplifying circuit and a playing device, including: N-order filters and an integrated circuit; after an original audio signal passes through the N-order filters, a filtered signal is obtained; after the filtered signal passes through the integrated circuit, a corresponding digital signal is output; where the number of operational amplifiers adopted in the N-order filters is smaller than N, and N is a natural number greater than 1.