Power Amplifier PWM Control with Pulse Width Adjustment
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Solution Overview
Problem
Conventional digital audio power amplifiers face limitations in performance improvement due to manufacturing constraints, as increasing the resolution of pulse width modulation (PWM) circuits requires higher operation frequencies, leading to increased production difficulty and cost.
Innovation Solution
A controller for a power amplifier that includes an oversampler, a controlling module, a PWM circuit, and a pulse width adjuster, which generates an oversampled signal, decomposes it into lower bit number control signals, and adjusts pulse widths to maintain performance without raising the PWM circuit's operation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the PWM circuit is increased to improve amplifier performance, then the performance improves, but the operation frequency must be raised which increases production difficulty and cost
Solution Approach 1:
The patent segments the high-resolution control signal into two separate control signals with lower bit numbers. The first control signal drives the PWM circuit at a lower frequency, while the second control signal adjusts the pulse width of the PWM output. This segmentation allows the system to achieve high effective resolution without requiring the PWM circuit to operate at high frequencies, thereby reducing manufacturing difficulty and cost.
Solution Approach 2:
The patent introduces a new dimension of control by separating amplitude control (via PWM duty cycle) from timing control (via pulse width adjustment). Instead of increasing PWM frequency to achieve higher resolution, the system uses a second control signal to adjust pulse width in the time domain, effectively adding a dimensional approach to resolution enhancement without increasing operational frequency.
2Measurement precision
If the operation frequency of the PWM circuit is raised to increase resolution, then the resolution improves, but the production cost and difficulty increase
Solution Approach 1:
The patent divides the high-resolution control requirement into two separate lower-resolution control signals. The first control signal operates at standard PWM frequencies with reduced bit depth, while the second control signal provides additional resolution through pulse width modulation. This segmentation reduces the complexity requirements for the PWM circuit while maintaining high effective resolution.
Solution Approach 2:
The patent changes the control parameters by introducing a second control signal that operates in parallel with the first. Instead of increasing the frequency parameter of the PWM circuit, the system modifies the control architecture to use two signals with different bit numbers, where the second signal adjusts pulse width to achieve the desired high resolution at lower frequencies.
Data Source
AI summary
A controller of a power amplifier includes an oversampler for oversampling an incoming digital signal to generate an oversampled signal, a controlling module for generating a first control signal and a second control signal according to the oversampled signal, a PWM circuit for generating a first PWM signal according to the first control signal, and a pulse width adjuster for adjusting a pulse width of the first PWM signal according to the second control signal to generate a second PWM signal for controlling a power stage of the power amplifier.