Adaptive Audio Voltage Limiting for Anti-Clipping Dynamic Range
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Solution Overview
Problem
Conventional audio systems fail to accurately regulate load voltage and battery current/power, leading to reduced output loudness, clipping, and compromised battery life due to ripple-induced voltage drops, which are not adequately addressed by existing sensing and filtering methods.
Innovation Solution
A voltage regulating circuit comprising a voltage limiter, filter, and selector dynamically adjusts the audio voltage threshold based on anti-clipping, power-based, and current-based limit signals, using real-time measurements and estimates of battery voltage, external series resistance, and load resistance to prevent clipping and optimize battery usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional sensing and filtering methods are used to measure and limit voltage, then the circuit complexity is reduced, but the voltage regulation precision deteriorates due to inability to accurately compensate for ripple
Solution Approach 1:
The patent implements dynamic voltage regulation by continuously monitoring the voltage rail and adjusting the audio voltage threshold in real-time based on detected ripple conditions. The system transitions from static filtering to dynamic adaptation, where the voltage threshold is modulated according to instantaneous battery voltage variations, thereby maintaining precision without excessive complexity.
Solution Approach 2:
The patent employs feedback mechanisms by sensing the voltage at the amplifier supply terminal and using this information to dynamically adjust the audio voltage threshold. The ripple detection and compensation circuitry creates a closed-loop system that continuously corrects for voltage variations, improving measurement precision while keeping the overall circuit architecture manageable through intelligent feedback control.
2Productivity
If the audio voltage threshold is increased to maximize output loudness, then the productivity is improved, but the reliability deteriorates due to clipping caused by voltage drops from battery ripple
Solution Approach 1:
The system dynamically adjusts the audio voltage threshold based on real-time detection of battery voltage ripple and instantaneous current draw conditions. By making the threshold adaptive rather than fixed, the system can maximize loudness during stable voltage conditions while automatically reducing the threshold when ripple-induced voltage drops occur, thereby preventing clipping and maintaining reliability.
Solution Approach 2:
The patent implements preliminary anti-action by detecting early signs of voltage rail droop due to ripple and preemptively adjusting the audio voltage threshold downward before clipping occurs. The ripple compensation circuitry anticipates potential voltage drops and counteracts them by modifying the threshold in advance, preventing the harmful effect of clipping while preserving maximum possible loudness.
3Reliability
If the audio voltage threshold is decreased to prevent clipping, then the reliability is improved, but the productivity deteriorates due to reduced output loudness and available headroom
Solution Approach 1:
Rather than using a statically decreased voltage threshold, the system dynamically modulates the threshold based on instantaneous battery voltage conditions. During periods of stable voltage, the threshold is maintained high to maximize loudness. When ripple-induced voltage drops are detected, the threshold is temporarily reduced only during those specific intervals, thereby maintaining reliability without permanently sacrificing output loudness or headroom.
4Stability of the object's composition
If heavily filtered voltage measurement is used to smooth out ripple, then the stability is improved, but the measurement precision deteriorates due to delayed response to instantaneous voltage changes
Solution Approach 1:
The patent segments the voltage measurement and processing into multiple stages: raw voltage sensing, ripple detection, filtering for stability, and dynamic threshold adjustment. By separating the measurement function into distinct processing paths, the system can apply filtering to maintain stability while preserving the ability to detect instantaneous changes through the ripple detection path, thereby achieving both stability and precision simultaneously.
Data Source
AI summary
An audio system includes an amplifier, regulating circuitry, and a filter. The regulating circuitry generates an audio voltage threshold signal based on an estimated value of the supply voltage source of the system, the estimated ESR between the system voltage supply and amplifier voltage supply pin, and the measured output resistance of the system. From these measurements/estimates, an anti-clipping voltage limit signal is generated. Power-budget-based and current-budget-based voltage limit signals are also determined based on first and second functions of the estimated value of the voltage source, respectively. The minimum of these three voltage limit signals is selected as the audio voltage threshold signal. The measurements, estimates and calculations are performed on a periodic basis to continually update the audio voltage threshold signal and thus adaptively regulate the audio system. A de-emphasis filter in the audio signal path compensates for capacitive ripple of the voltage at the amplifier's voltage supply pin.