Audio Amplifier Power Feedback for Loudspeaker Impedance Distortion
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Solution Overview
Problem
Conventional audio amplifiers face issues with output power variation due to nonlinear impedance changes in loudspeakers, leading to distortion and reduced sound quality, as well as potential damage from uneven frequency/impedance characteristics.
Innovation Solution
A power feedback control amplifier structure incorporating a power amplifying unit, current sensing unit, voltage sensing unit, and multiplying unit forms a closed loop feedback system to maintain constant output power by converting output current and voltage signals into control signals, which are multiplied and fed back to the input side to stabilize power amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional audio amplifier circuit structure is used, then the amplifier can output power to the loudspeaker, but the output power varies due to nonlinear impedance changes in the loudspeaker, causing distortion and reduced sound quality
Solution Approach 1:
The patent implements a power feedback control mechanism where the output power is sensed through current and voltage sensing units, processed by a multiplying unit to calculate actual power, and fed back to the input side of the power amplifier. This closed-loop feedback system dynamically adjusts the amplification to compensate for loudspeaker impedance variations, maintaining consistent output power and reducing distortion caused by nonlinear impedance characteristics.
2Reliability
If the amplifier operates without power feedback control, then the circuit structure is simple, but the amplifier may be damaged due to insufficient maximum power bearing capacity from impedance variations
Solution Approach 1:
The power feedback control circuit continuously monitors the actual output power by multiplying current and voltage signals, compares it with the desired power level, and adjusts the input signal accordingly. This feedback mechanism prevents the amplifier from being overloaded by detecting when the output power exceeds safe limits due to low impedance conditions, thereby protecting the amplifier without requiring complex external protection circuits.
3Ease of operation
If natural frequency/impedance characteristics of the loudspeaker are allowed to affect output, then the loudspeaker can operate freely, but the playback music distortion occurs and output quality deteriorates
Solution Approach 1:
The feedback control system allows the loudspeaker to operate freely across its entire impedance range without requiring manual adjustment or restriction. The multiplying unit calculates the actual power delivered to the loudspeaker regardless of impedance variations, and the feedback mechanism automatically compensates for these variations, maintaining constant output power and eliminating distortion while preserving the loudspeaker's natural operating characteristics.
Data Source
AI summary
The present invention generally relates to a structure and method of audio amplifier with power feedback, including a power amplifying unit, a loud-speaker, a current sensing unit, a voltage sensing unit and a multiplying unit. The power amplifying unit includes an input side and an output side, the input side inputs an audio voltage signal, and the loudspeaker is electrically connected to an output side of the power amplifying unit. The current sensing unit is electrically connected to the output side of the power amplifying unit and senses the output current of the power amplifying unit and then converts it into a current control voltage signal. The voltage sensing unit is electrically connected to the output side of the power amplifying unit, and senses the output voltage of the power amplifying unit to form an output sensing voltage signal. The multiplying unit obtains the voltage of the current control voltage multiplied by the output sensing voltage, and the output side of the multiplying unit is electrically connected to the input side of the power amplifying unit to form a closed loop power feedback structure. Accordingly, the output quality of the amplifier and loud-speaker is improved.