Audio Power Limiter Feedback Circuit for Burst Waveform Preservation
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Solution Overview
Problem
Power limiting circuits struggle to handle burst power waveforms effectively, as existing feedback compressors attenuate signals prematurely due to varying load impedance with frequency, leading to failure in passing unattenuated burst waveforms even when the average power is within limits.
Innovation Solution
A feedback compressor circuit configuration that combines an auxiliary attenuation signal with a compressed attenuation signal from a feedback compressor circuit, using a low-pass filter to delay attenuation and preserve burst power waveforms by determining the threshold power level dynamically, allowing the amplifier to output a 1200 W burst while maintaining an average power below 300 W.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a feedback compressor attenuates the signal when power exceeds the threshold, then the average power is limited, but the burst power waveform is distorted and attenuated
Solution Approach 1:
The system performs preliminary action by measuring the instantaneous power and predicting future power levels before the threshold is exceeded. The controller applies attenuation in advance based on predicted power levels, allowing burst waveforms to pass through unattenuated while preventing average power from exceeding the threshold. This is achieved by continuously monitoring and predicting power trends rather than reacting after threshold violation occurs.
2Power
If attenuation is applied immediately when power exceeds threshold, then power limiting is effective, but burst waveforms fail to pass unattenuated
Solution Approach 1:
The system dynamically adjusts the attenuation amount based on the duration and characteristics of the power exceedance. For brief burst waveforms that exceed the threshold, the controller applies minimal or no attenuation, allowing them to pass through unattenuated. For sustained power exceedances, the controller applies progressive attenuation. This dynamic response is achieved by monitoring the temporal characteristics of power deviations and adjusting attenuation accordingly.
3Speed
If the low-pass filter time constant is reduced to respond faster, then attenuation is applied more quickly, but burst waveforms are attenuated prematurely
Solution Approach 1:
The system performs preliminary action by predicting future power levels based on current and historical measurements, eliminating the need for aggressive low-pass filtering. The controller uses these predictions to apply attenuation in advance when necessary, achieving fast response without the signal processing lag that causes premature attenuation of burst waveforms. This predictive approach replaces the traditional reactive filtering method.
Data Source
AI summary
Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, multiplying the received audio signal with a power feedback signal to create a product audio signal, wherein the feedback signal comprises a low-pass filtered signal, applying a power amplifier to the product audio signal, and providing the amplified product audio signal as an output signal to a speaker.