Floating-Supply Power Amplifier Feedback for Series Output Stages
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Solution Overview
Problem
Existing power amplifiers struggle to connect output stages in series due to difficulties in designing feedback circuits for appropriate feedback operations, limiting the ability to increase voltage applied to speakers beyond the output voltage of a single power amplifier.
Innovation Solution
A power amplifier configuration that includes a signal input unit, an electrically isolated output stage driven by a floating power supply, a reference potential switch between the power supply's reference node and a reference potential line, and a feedback circuit that amplifies and feeds back differential voltage between the output stage and the reference node, allowing for series connection of power amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If output stages of power amplifiers are connected in series to increase voltage applied to speaker, then voltage output is improved, but feedback circuit operation becomes difficult due to different output signals
Solution Approach 1:
The feedback circuit is segmented into individual feedback circuits for each power amplifier unit. Each feedback circuit independently processes the output signal of its associated power amplifier, allowing series connection of multiple amplifiers while maintaining proper feedback operation for each unit without requiring complex inter-dependent feedback design.
Solution Approach 2:
The invention establishes a common reference potential for all feedback circuits in the series-connected power amplifiers. By providing a shared reference potential, the feedback circuits can operate independently with equal footing, eliminating the complexity that would arise from different reference levels and enabling straightforward feedback design despite series connection.
2Ease of operation
If conventional power amplifier configuration is used, then feedback circuit operation is simple, but voltage applied to speaker is limited to output voltage of one power amplifier
Solution Approach 1:
The system is segmented into independent power amplifier modules, each with its own feedback circuit. This modular approach allows multiple units to be series-connected to achieve higher voltage output while each module maintains simple, independent feedback operation, combining the benefits of high voltage capability with ease of feedback circuit operation.
Solution Approach 2:
The power amplifier is designed with universal feedback circuit architecture that functions effectively both in standalone configuration and in series-connected configurations. The feedback circuit can operate with a single amplifier or with multiple series-connected amplifiers, providing multi-functionality without requiring different circuit designs for different operating modes.
Data Source
AI summary
A power amplifier includes a signal input unit to which an input signal is applied, an output stage that is electrically isolated from the signal input unit, where the output stage is configured to amplify an output signal of the signal input unit based on a power supply voltage from a floating power supply, a reference potential switch that is inserted between a reference node of the power supply voltage generated by the floating power supply and a reference potential line, and a feedback circuit configured to amplify a differential voltage between an output node of the output stage and the reference node, and feed the resultant voltage back to the signal input unit.