Audio Power Limiter Circuit for Burst Waveform Integrity

Solution Overview

Problem

Power limiter circuits fail to accurately manage burst power waveforms, leading to attenuation of signals even when the average power is below the threshold, due to the complex relationship between amplitude and output power, which varies with frequency and load impedance.

Innovation Solution

A feedback compressor circuit 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 determine the attenuation amount and generate an audio output signal, thereby preserving burst power waveforms by smoothing power measurements and adjusting the threshold dynamically.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a feedback compressor applies attenuation as soon as output exceeds threshold, then power limiting is effective, but burst signals are prematurely attenuated even when average power is below threshold

Engineering Contradiction:

Improvepower limiting effectivenessVSAvoidsignal transmission accuracy

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary action by measuring and storing power values over time before making attenuation decisions. The low-pass filter pre-processes the power measurement to predict future power levels, allowing the system to prepare appropriate attenuation settings in advance rather than reacting immediately to threshold crossings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the attenuation amount based on the rate of change of power and the duration of threshold exceedance. Rather than applying fixed attenuation, the system adapts the attenuation level to match the actual power conditions, enabling it to distinguish between transient bursts and sustained high-power conditions.

Inventive Principle:

Principle #15Dynamics

2Power

If a simple compressor limits power at any point in time, then instantaneous power control is achieved, but burst waveforms fail to pass unattenuated

Engineering Contradiction:

Improveinstantaneous power controlVSAvoidburst waveform integrity

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The system performs preliminary action by measuring and storing power values over time before making attenuation decisions. The low-pass filter pre-processes the power measurement to predict future power levels, allowing the system to prepare appropriate attenuation settings in advance rather than reacting immediately to threshold crossings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the attenuation amount based on the rate of change of power and the duration of threshold exceedance. Rather than applying fixed attenuation, the system adapts the attenuation level to match the actual power conditions, enabling it to distinguish between transient bursts and sustained high-power conditions.

Inventive Principle:

Principle #15Dynamics

3Productivity

If power measurement is smoothed with low-pass filter, then premature attenuation is prevented, but response time to actual power limits is delayed

Engineering Contradiction:

Improvesignal transmission accuracyVSAvoidpower limit response time

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The system dynamically adjusts the attenuation amount based on the rate of change of power and the duration of threshold exceedance. Rather than applying fixed attenuation, the system adapts the attenuation level to match the actual power conditions, enabling it to distinguish between transient bursts and sustained high-power conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the measured power conditions and their rate of change to continuously adjust the attenuation amount. This closed-loop approach allows the system to respond appropriately to actual power limit conditions while filtering out transient variations, balancing response time with measurement accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11398801B2Power limiter configuration for audio signals

Publication Date: 2022.07.26 BIAMP SYST LLC

AI summary

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an 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.