Audio Amplifier Distortion Correction for HOR and ZOR Modes
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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 limited battery capacity.
Innovation Solution
An audio amplification system with a digital audio path and an audio amplifier that includes a controller to compensate for charge diversion, utilizing HOR and ZOR modes with a correction block to adjust the digital signal and correct for parasitic effects, and a closed-loop architecture with digital PWM control for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the audio amplifier operates in conventional mode without correction, then the circuit is simple, but audio fidelity deteriorates due to parasitic effects causing charge diversion
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 compensation signals to counteract the parasitic effects of the output capacitor, thereby improving audio fidelity without fundamentally redesigning the entire amplifier circuit.
Solution Approach 2:
The patent segments the audio amplification system into distinct functional blocks: the digital audio path, the correction block, and the amplifier stage. The correction block is further segmented into sub-functions including parasitic effect calculation, compensation signal generation, and signal combination. This modular segmentation allows for targeted improvement of audio fidelity while managing circuit complexity.
2Loss of energy
If the audio amplifier uses high output resistance (HOR) mode, then power efficiency is improved, but distortion increases due to parasitic capacitance effects
Solution Approach 1:
The correction block performs preliminary anti-action by calculating the expected charge diversion caused by parasitic capacitance in HOR mode and applying a compensating signal before the distortion occurs. This preemptive correction allows the amplifier to operate in power-efficient HOR mode while maintaining signal quality.
Solution Approach 2:
The system implements feedback mechanisms where the correction block continuously monitors the amplifier's operating state and adjusts the compensation signal accordingly. This feedback loop ensures that power efficiency is maintained while dynamically correcting for parasitic effects that vary with operating conditions.
3Manufacturing precision
If the audio amplifier uses zero output resistance (ZOR) mode, then audio fidelity is improved, but power consumption increases
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting the output resistance characteristic of the amplifier between HOR and ZOR modes based on the audio signal characteristics and power conditions. The correction block compensates for parasitic effects in both modes, enabling the system to switch between power efficiency (HOR) and audio fidelity (ZOR) as needed.
Solution Approach 2:
The system dynamically switches between HOR and ZOR modes and adjusts the correction block's compensation parameters in real-time based on operating conditions. This dynamic adaptation allows the amplifier to optimize the trade-off between power consumption and audio fidelity during different phases of operation.
4Loss of energy
If parasitic effects are not corrected, then the device complexity is low, but charge diversion reduces power efficiency
Solution Approach 1:
The correction block serves as an intermediary that efficiently handles the complex calculations and compensation operations, allowing the rest of the amplifier circuit to remain relatively simple. This intermediary approach improves power efficiency without requiring a complete redesign of the entire system.
Solution Approach 2:
The patent replaces complex analog compensation circuits with a digital correction block that uses computational methods to achieve the same effect. This substitution of digital processing for analog circuitry improves power efficiency while keeping the overall device complexity manageable through software/firmware implementation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances audio fidelity and power efficiency by minimizing parasitic losses and optimizing power usage in wearable audio devices.
Implementation Method 1
parasitic effect of the audio amplifier
Data Source
AI summary
Distortion correction for audio amplifiers can be implemented in an audio driver that 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.