Digital Amplifier Switching for Short PWM Pulse Linearity
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Solution Overview
Problem
Digital amplifiers experience distortion due to short pulse widths of PWM signals, leading to degraded sound quality in audio output, as semiconductors in the switch module struggle to perform switching operations effectively.
Innovation Solution
A switching device and method that utilize an MLP signal and compensating signals to manage pulse widths, ensuring the switch module operates within optimal parameters by adjusting pulse widths based on predefined conditions, thereby preventing distortion. The MLP signal and compensating signals are strategically timed and overlapping/adjacent to maintain signal linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pulse width of the PWM signal is reduced to achieve higher efficiency and faster switching, then power efficiency is improved, but distortion occurs in the output signal due to insufficient switching time
Solution Approach 1:
The patent applies preliminary action by extending the pulse width of PWM signals below a predetermined threshold to a minimum pulse width before transmission to the switch module. This pre-processing ensures that even signals intended to be very short maintain sufficient duration for reliable semiconductor switching, preventing distortion while preserving the energy efficiency benefits of PWM operation.
Solution Approach 2:
The patent changes the pulse width parameter dynamically based on signal characteristics. When the original pulse width is below the predetermined threshold, it is extended to the minimum pulse width; otherwise, it remains unchanged. This parameter adjustment resolves the contradiction by ensuring adequate switching time only when necessary, maintaining signal linearity without unnecessarily increasing power consumption.
2Manufacturing precision
If the pulse width of the PWM signal is made sufficiently long to ensure proper switching operation, then signal linearity is maintained, but the switching efficiency and responsiveness of the digital amplifier deteriorates
Solution Approach 1:
The patent applies partial action by selectively extending pulse widths only when necessary - specifically, only when the original pulse width is below the predetermined threshold. Signals with adequate pulse widths are transmitted unchanged, avoiding unnecessary extension that would reduce switching efficiency. This selective approach maintains signal linearity where needed while preserving switching performance where adequate margins already exist.
3Reliability
If the minimum pulse width is increased to prevent distortion, then switching reliability is improved, but the maximum frequency response and signal fidelity are reduced
Solution Approach 1:
The patent applies preliminary action by pre-extending only those pulse widths that fall below the reliability threshold, rather than uniformly increasing all pulse widths. This selective extension ensures adequate switching reliability for problematic signals while preserving the original timing characteristics of signals that already meet reliability requirements, thereby maintaining frequency response and signal fidelity.
Data Source
AI summary
A switching device of a digital amplifier and a method for controlling the same are disclosed. In accordance with the present invention, a linearity is maintain even for a short pulse width since a data signal having a pulse width shorter than a predetermined length. Moreover, when an MLP signal is located at both sides of a compensating signal without overlapping with each other, a problem due to a common mode may be prevented.