PWM Mapper Architecture for 3-Output Class-D Headphone Amplifiers
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Solution Overview
Problem
Conventional Class-D power amplifiers for stereo earphones or headphones face issues with disturbance behavior and loss factors due to their differential pulse width modulation design, which requires four outputs but only three are needed for earphones or headphones.
Innovation Solution
A pulse width modulation system with two PWM mappers for mono audio channels and a reference signal, using interpolation filters, summation elements, filters, quantizers, and PWM mappers to generate pulse signals that reduce signal distortions and can be used in Class-D power amplifiers with three outputs by creating a differential mono or stereo pulse width modulated audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If differential pulse width modulation is used in Class-D power amplifiers for stereo earphones or headphones, then the amplifier can provide stereo audio output, but the disturbance behavior and loss factor worsen due to requiring four outputs instead of three
Solution Approach 1:
The patent extracts the DC middle potential generation function from the conventional differential PWM architecture. By separating the DC component generation (performed once for the reference signal) from the audio signal processing, the system eliminates the need for four output stages while maintaining stereo capability through three outputs, thereby reducing energy loss and improving efficiency
Solution Approach 2:
The reference signal serves multiple functions simultaneously: it provides the DC middle potential, acts as a carrier for PWM modulation, and enables both mono and stereo audio output configurations. This multi-functionality allows the amplifier to adapt to different output requirements (3 outputs for earphones, 4 outputs for speakers) without requiring separate circuit implementations, thus improving adaptability while reducing energy loss
2Adaptability or versatility
If differential pulse width modulation is used in Class-D power amplifiers for stereo earphones or headphones, then the amplifier can provide stereo audio output, but the disturbance behavior worsens due to requiring four outputs instead of three
Solution Approach 1:
The patent extracts the DC middle potential generation function from the conventional differential PWM architecture. By separating the DC component generation (performed once for the reference signal) from the audio signal processing, the system eliminates the need for four output stages while maintaining stereo capability through three outputs, thereby reducing energy loss and improving efficiency
Solution Approach 2:
The reference signal serves multiple functions simultaneously: it provides the DC middle potential, acts as a carrier for PWM modulation, and enables both mono and stereo audio output configurations. This multi-functionality allows the amplifier to adapt to different output requirements (3 outputs for earphones, 4 outputs for speakers) without requiring separate circuit implementations, thus improving adaptability while reducing energy loss
Data Source
AI summary
A system, a device and a method for pulse width modulation is disclosed. One embodiment includes a pulse width modulation device, a first pulse width modulation mapper for pulse width modulation of a data signal, or a signal derived therefrom, and a second pulse width modulation mapper for pulse width modulation of a reference signal, or a signal derived therefrom. In one or more embodiments, the data signal e.g., can be a signal for a mono audio channel, or a signal for a stereo audio channel. The reference signal can be a signal including a constant signal level or a signal including a non-constant signal level an offset signal.