Open-Loop Class-D Amplifier Gain Compensation for Variable Supply
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio amplifiers, particularly class-D amplifiers, face challenges in maintaining consistent gain due to variations in supply voltage, leading to inefficiencies and potential distortion in audio output.
Innovation Solution
A system comprising a digital modulator, a digital gain element, an open-loop Class-D amplifier powered by a variable supply voltage, and a control circuit that adjusts the digital gain to compensate for changes in the analog gain caused by supply voltage variations, ensuring consistent audio output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a class-D amplifier uses a variable power supply to improve power efficiency, then power dissipation is reduced, but gain consistency deteriorates due to supply voltage variations
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the supply voltage to the Class-D amplifier and adjusts the digital gain accordingly. When supply voltage varies, the control circuit detects this change and modifies the digital gain to compensate, thereby maintaining consistent overall gain despite the variable power supply conditions.
Solution Approach 2:
The patent changes the parameter of digital gain dynamically in response to supply voltage variations. By adjusting the digital gain parameter based on the actual supply voltage conditions, the system compensates for gain inconsistencies caused by the variable power supply, thus maintaining reliable audio output levels.
2Device complexity
If a class-D amplifier operates with fixed gain architecture, then circuit complexity is reduced, but adaptability to varying supply voltage deteriorates
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the variable power supply and the Class-D amplifier. This control circuit acts as a mediator that translates supply voltage variations into appropriate digital gain adjustments, enabling the amplifier to adapt to varying supply conditions without fundamentally changing the Class-D amplifier architecture itself.
Solution Approach 2:
The patent makes the gain characteristic dynamic by implementing a control circuit that continuously adjusts the digital gain based on real-time supply voltage conditions. This transforms the previously static gain architecture into a dynamic system that automatically adapts to varying supply voltage, enhancing versatility without requiring a complete architectural redesign.
Data Source
AI summary
A system may include a digital modulator configured to modulate an input signal received at an input of the digital modulator to generate a modulated input signal at an output of the digital modulator, a digital gain element having a digital gain and coupled to the digital modulator, an open-loop Class-D amplifier coupled to an output of the digital modulator and configured to amplify the modulated input signal, wherein the open-loop Class-D amplifier is powered from a variable power supply having a variable supply voltage which is variable in response to one or more characteristics of the input signal, and a control circuit configured to control the digital gain to approximately cancel changes in an analog gain of the open-loop Class-D amplifier due to variation in the variable supply voltage in response to the one or more characteristics of the input signal.