Feedback Compressor Circuit for Preserving Audio Burst Power
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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 audio signal with an auxiliary attenuation signal and 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 for efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a feedback compressor applies attenuation when output power exceeds threshold, then average power is limited below threshold, but burst power waveforms are attenuated prematurely even when average power is within limits
Solution Approach 1:
The patent applies dynamic time-varying attenuation where the compression amount changes over time based on the integration of power excess. During burst waveforms, the integrated power excess remains below threshold for short durations, allowing unattenuated passage. For sustained high power, the integrated value exceeds threshold, triggering appropriate attenuation. This dynamic approach resolves the contradiction by adapting attenuation behavior to the temporal characteristics of the input signal.
Solution Approach 2:
The system performs preliminary integration of power excess before applying attenuation. By accumulating the power excess over time in an integrator, the system prepares a measure of total energy deviation that precedes the attenuation decision. This preliminary action allows the system to distinguish between transient bursts (where integration hasn't reached threshold) and sustained high power (where integration has exceeded threshold), preventing premature attenuation of valid bursts.
2Device complexity
If load impedance varies with frequency, then output power calculation becomes complex, but simple voltage-based power measurement is inaccurate
Solution Approach 1:
The patent uses feedback from actual output power measurement (via voltage and current sensors) to control the compression amount. The measured output power is fed back to the integrator, which accumulates the difference between actual and threshold power. This feedback mechanism eliminates the need for complex predictive modeling of load impedance, as the system directly measures what is actually delivered to the load, resolving the contradiction between measurement accuracy and calculation complexity.
Solution Approach 2:
The system uses itself to measure its own output power through integrated voltage and current sensing circuits. Rather than requiring external complex modeling, the amplifier system self-monitors its actual power delivery by measuring voltage across and current through the output terminals. This self-service approach provides accurate real-time power measurement without external 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, receiving an auxiliary attenuation signal from an auxiliary attenuation source, determining a threshold power level based on a value of the auxiliary attenuation signal, determining an output power level of the audio signal exceeds the threshold power level, combining the audio signal with the auxiliary attenuation signal from the auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.