Feedback Compressor Circuit for Burst-Safe Audio Power Limiting
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Solution Overview
Problem
Power limiting circuits fail to accurately manage burst power waveforms, leading to attenuation of signals even when the average power is within limits, due to the complex relationship between amplitude and output power, which varies with frequency, causing inefficiencies in amplifier output.
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 determine the attenuation amount and apply it to the audio signal, allowing for dynamic adjustment of the threshold and filter state to preserve burst power waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a feedback compressor applies attenuation whenever output power exceeds the threshold, then the average power is limited, but burst power waveforms are incorrectly attenuated even when their average power is within limits
Solution Approach 1:
The patent applies dynamics by making the compression behavior adaptive based on the temporal characteristics of the input signal. The system dynamically adjusts whether to apply compression by detecting burst waveforms and temporarily disabling compression during these short-duration high-power events. This allows the system to maintain accurate average power limiting for continuous signals while preserving burst power output capability, resolving the contradiction between power limiting accuracy and burst power productivity.
2Measurement precision
If the load impedance is modeled to predict output power, then power measurement accuracy improves, but computational cost and latency increase
Solution Approach 1:
The patent uses feedback by directly measuring the actual output power through voltage and current sensors rather than attempting to predict it through load impedance modeling. The measured power is fed back to the compression controller, which uses this accurate real-time information to make compression decisions. This feedback-based measurement approach achieves high measurement precision without the computational overhead and latency associated with predictive modeling.
3Device complexity
If a simple compression threshold is used, then the circuit complexity is reduced, but burst power waveforms cannot pass unattenuated
Solution Approach 1:
The patent resolves this contradiction by introducing dynamic burst detection and temporary compression disabling. The system maintains a simple compression threshold circuit but adds a burst detection mechanism that identifies short-duration high-power waveforms. When a burst is detected, the system dynamically disables compression for the duration of the burst, allowing these signals to pass unattenuated. This dynamic approach preserves burst signal transmission capability without significantly increasing circuit complexity.
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.