Digital Audio Amplifier Feedback for Distortion and EMI Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital audio amplifiers introduce non-linearity and noise into output signals, known as distortion, which affects signal quality and playback time in portable devices, especially with the constraints of smaller device sizes and battery capacity.
Innovation Solution
Incorporating digital feedback of output audio signals with circuitry to compensate for distortion, using a combination of class D and class AB amplifiers to operate in energy-efficient modes, reducing electromagnetic interference and power supply noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital feedback and distortion compensation circuitry are incorporated, then signal quality is enhanced and distortion is reduced, but device complexity increases
Solution Approach 1:
The patent implements digital feedback by capturing the output audio signal and feeding it back through distortion compensation circuitry. The system analyzes the output signal for distortion components and adjusts the amplification process to compensate for detected non-linearities, thereby improving signal quality through continuous monitoring and correction
Solution Approach 2:
The patent introduces an intermediate digital signal processing stage between the amplifier output and the feedback input. This intermediary processing stage extracts distortion components from the output signal and generates compensation signals without requiring direct modification of the main amplification path, thus improving signal quality while managing complexity
2Use of energy by moving object
If class D amplifiers are used for energy efficiency, then power consumption is reduced and playback time is extended, but electromagnetic interference and power supply noise increase
Solution Approach 1:
The system uses digital feedback to detect electromagnetic interference and power supply noise in the output signal. By continuously monitoring for these harmful factors and generating compensation signals, the system maintains the energy efficiency of class D operation while actively reducing the impact of EMI and noise on audio quality
Solution Approach 2:
The patent converts the electromagnetic interference and power supply noise generated by class D amplification into detectable signal components. The feedback system identifies these harmful factors and uses them to generate corrective compensation signals, thereby transforming the harmful EMI and noise into useful information for improving output quality
3Volume of moving object
If smaller device sizes are produced, then device dimensions are reduced, but battery capacity and playback time are constrained
Solution Approach 1:
The patent changes the operational parameters of the amplifier by implementing dynamic switching between different amplification modes and utilizing distortion compensation to maintain high efficiency. This allows the system to achieve extended playback time in compact devices by optimizing power consumption characteristics without sacrificing audio quality
Solution Approach 2:
The digital feedback system monitors power consumption and output signal quality in real-time, allowing the amplifier to dynamically adjust its operating parameters. This enables compact devices to maintain extended playback time by optimizing efficiency while compensating for distortion, achieving both small size and long duration performance
Data Source
AI summary
An embodiment of an electronic system includes a digital audio amplifier having a continuous time modulator adapted to generate a difference signal between an audio bitstream and a feedback signal, and to perform a modulation process on the difference signal to generate an input pulse modulated signal, a class D output stage adapted to receive, quantize, and amplify the input pulse modulated signal to generate an output pulse modulated signal, and a feedback path adapted to provide the output pulse modulated signal as the feedback signal to the continuous time modulator. Another embodiment includes a class AB output stage adapted to receive and amplify an input digital audio signal to generate an analog output signal, and circuitry adapted to enable the digital audio amplifier to be configured to enable the class AB output stage and to disable the class D output stage.