Audio Amplifier Correction for HOR/ZOR Parasitic Capacitance
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Solution Overview
Problem
Wearable audio devices face challenges in achieving high-fidelity audio reproduction while operating in a power-efficient manner due to parasitic effects and parasitic charge diversion in audio amplifiers, which affect the load.
Innovation Solution
An audio amplification system with a digital audio path and a correction block that adjusts the digital signal to compensate for charge diversion, incorporating a controller to manage parasitic effects and support high output resistance (HOR) and zero output resistance (ZOR) modes, enhancing audio performance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If audio amplifier operates in conventional mode without correction, then circuit complexity is low, but audio fidelity deteriorates due to parasitic effects
Solution Approach 1:
The patent introduces a correction block as an intermediary component between the digital audio path and the amplifier output. This block calculates and applies correction signals that compensate for parasitic effects (such as capacitance from disabled ZOR driver) without requiring fundamental changes to the amplifier architecture, thereby improving audio fidelity while adding only moderate complexity.
Solution Approach 2:
The system implements a feedback mechanism where the controller monitors the amplifier's operating state (HOR/ZOR mode transitions) and dynamically adjusts the digital signal through the correction block. This closed-loop approach ensures continuous compensation for parasitic effects, maintaining high audio fidelity across different operating conditions.
2Measurement precision
If audio amplifier uses parasitic correction, then audio fidelity is improved, but power consumption increases
Solution Approach 1:
The correction system is designed to be dynamic rather than static. The controller activates the correction block only when necessary (during HOR/ZOR mode transitions where parasitic effects occur), and adjusts correction strength based on the current operating state. This dynamic operation minimizes power consumption while maintaining audio fidelity when correction is needed.
Solution Approach 2:
The system changes operational parameters dynamically - switching between different correction levels or disabling correction during steady-state operation where parasitic effects are minimal. This parameter adjustment allows the system to balance power consumption and audio fidelity based on real-time operating conditions.
3Use of energy by moving object
If audio amplifier switches between HOR and ZOR modes, then power efficiency is improved, but audio fidelity deteriorates due to charge diversion
Solution Approach 1:
The correction block performs preliminary calculations of the parasitic charge diversion before it affects the audio output. By predicting the charge that will be diverted during HOR/ZOR mode transitions and pre-calculating the necessary compensation, the system maintains audio fidelity while allowing efficient mode switching.
Solution Approach 2:
The system applies preliminary anti-action by introducing correction signals that counteract the parasitic effects before they can degrade audio quality. The correction block generates compensating signals that oppose the charge diversion caused by parasitic capacitance, thereby preventing fidelity deterioration during mode transitions.
Data Source
AI summary
In some embodiments, an audio driver includes an audio amplifier configured to operate in a high output resistance (HOR) mode with an HOR driver or a zero output resistance (ZOR) mode with a ZOR driver, The audio amplifier includes an output node coupled to both of the HOR driver and the ZOR driver, such that the output node is subject to an effect of the ZOR driver in a disabled state when the audio amplifier is operating in the HOR mode. The audio driver further includes a control system configured to correct for the effect of the disabled ZOR driver by adjusting an input signal.