Audio Amplifier Window Circuit for Low-Power Gain Calibration
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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 limited battery capacity and the need for effective gain calibration in high-output resistance mode.
Innovation Solution
A window circuit is introduced that includes a pulse train generator and M-1 accumulators to transform rectangular pulses into an M-th order window, used in a calibration circuit for gain adjustment based on tone frequency, implemented in audio amplification systems for wearable devices like wireless headphones or earphones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain calibration is performed in high-output resistance mode for audio amplifiers, then audio fidelity is improved, but power consumption increases and battery life decreases
Solution Approach 1:
The patent applies preliminary action by performing gain calibration during manufacturing or initial setup when the device is stationary and power availability is not constrained. The calibration results are stored for later use during normal operation, allowing high-precision calibration to be done once rather than continuously, thus achieving accurate gain calibration without ongoing power consumption penalties.
Solution Approach 2:
The system uses self-service by implementing automatic calibration routines that execute without user intervention and store calibration data for autonomous reuse. The amplifier system automatically applies stored calibration parameters during operation, eliminating the need for continuous power-intensive calibration processes while maintaining audio fidelity.
2Measurement precision
If continuous gain calibration is performed to maintain audio fidelity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the calibration function into a separate, dedicated calibration circuit module that operates independently from the main audio processing path. This modular approach allows the calibration subsystem to be optimized separately, reducing the complexity burden on the overall system while maintaining high measurement precision through specialized calibration hardware.
Solution Approach 2:
By performing calibration preliminarily and storing results, the system eliminates the need for continuous complex calibration operations. The stored calibration data simplifies ongoing operation, allowing the system to maintain audio fidelity through simple parameter application rather than repeated complex calibration procedures.
3Measurement precision
If high-output resistance mode is used to improve audio quality, then sound fidelity is improved, but power efficiency deteriorates
Solution Approach 1:
The patent implements dynamics by enabling the amplifier to dynamically switch between high-output resistance mode and standard mode based on operational requirements. The system uses the power-intensive high-output resistance mode only when audio fidelity is prioritized (such as during calibration or high-quality audio playback), and switches to power-efficient standard mode for normal operation, thus optimizing the trade-off between audio quality and power consumption.
Solution Approach 2:
By pre-calibrating the amplifier in high-output resistance mode during manufacturing, the system establishes accurate performance characteristics that can be maintained during normal operation without continuously operating in the power-intensive mode. This preliminary calibration allows the amplifier to achieve high audio fidelity during standard operation without the ongoing power penalty of maintaining high-output resistance mode continuously.
Data Source
AI summary
In some embodiments, a window circuit for an audio amplification system can include a pulse train generator configured to generate a train of rectangular pulses having M amplitude values, with the quantity M being an integer greater than 1, and M-1 accumulators arranged in series to transform the train of rectangular pulses into an output that is representative of an M-th order window. In some embodiments, such a window circuit can be utilized for a calibration circuit that includes a gain adjustment circuit configured to generate a correction signal to compensate for a gain variation of an audio amplifier based at least in part on a window of frequency at or about a frequency of a calibration tone applied to the audio amplifier.