Hybrid Class-D Amplifier With DAC Feedback to Cut Op-Amp Power

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Solution Overview

Problem

Current audio playback systems consume excessive power due to the use of multiple operational amplifiers in output driving circuits, necessitating a reduction in their number to enhance performance and reduce power consumption.

Innovation Solution

A hybrid class-D amplifier architecture that incorporates a digital-to-analog conversion (DAC) input stage circuit, loop filter circuit, quantizer circuit, and feedback circuit, where the DAC input stage reduces the need for operational amplifiers by converting digital signals into analog signals, and the loop filter and quantizer circuits generate filtered and quantized signals for power amplification, respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple operational amplifiers are used in the output driving circuit, then the audio signal can be properly amplified and driven, but the power consumption increases significantly

Engineering Contradiction:

Improvepower amplification capabilityVSAvoidpower consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent replaces traditional operational amplifier-based analog amplification with a digital pulse-density modulation (PDM) based amplification system. The digital domain processing substitutes for the analog operational amplifier circuitry, fundamentally changing the approach from analog electronics to digital signal processing for power amplification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters by switching from continuous analog voltage signals processed by operational amplifiers to discrete digital PDM signals. This parameter change from analog to digital domain enables more efficient power consumption characteristics while maintaining audio signal amplification capability

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If multiple operational amplifiers are used in the output driving circuit, then the audio signal processing can be completed, but the device complexity increases

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidnumber of operational amplifiers

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges multiple separate operational amplifier stages into a unified digital PDM processing architecture. By combining the functions of multiple analog amplifiers into a single digital signal processing path, the system reduces component count and overall device complexity while maintaining signal processing capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The digital PDM processing circuit serves multiple functions simultaneously - it performs signal conversion, filtering, and amplification that were previously handled by separate operational amplifier stages. This multi-functionality reduces the need for multiple specialized components

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 configuration minimizes the number of operational amplifiers, thereby reducing overall power consumption and improving audio playback performance without introducing significant side effects, while maintaining cost-effectiveness.

Implementation Method 1

The DAC input stage circuit may be configured to convert a digital signal into an analog signal

Methodology Applied

Scientific EffectDigital-to-analog conversion:

Implementation Method 2

The loop filter circuit may be configured to generate a filtered signal according to the analog signal and a feedback signal

Methodology Applied

Scientific EffectSignal filtering: Filter (electronic)

Implementation Method 3

The quantizer circuit may be configured to perform a quantization operation on the filtered signal to generate a quantized signal

Methodology Applied

Scientific EffectQuantization:

Implementation Method 4

The output stage circuit may be configured to perform power amplification on the quantized signal to generate an output signal

Methodology Applied

Scientific EffectPower amplification:

Implementation Method 5

The feedback circuit may be configured to generate the feedback signal according to the output signal

Methodology Applied

Scientific EffectFeedback: Feedback

Data Source

PatentUS20230387870A1Hybrid class-d amplifier

Publication Date: 2023.11.30 REALTEK SEMICON CORP

AI summary

A hybrid class-D amplifier is provided. The hybrid class-D amplifier includes a digital-to-analog conversion (DAC) input stage circuit, a loop filter circuit electrically coupled to the DAC input stage circuit, a quantizer circuit electrically coupled to the loop filter circuit, an output stage circuit electrically coupled to the quantizer circuit, and a feedback circuit electrically coupled between the output stage circuit and the loop filter circuit. The DAC input stage circuit converts a digital signal into an analog signal. The loop filter circuit generates a filtered signal according to the analog signal and a feedback signal. The quantizer circuit performs a quantization operation on the filtered signal to generate a quantized signal. The output stage circuit performs power amplification on the quantized signal to generate an output signal. The feedback circuit generates the feedback signal according to the output signal.