Audio Amplifier Gain Calibration Using Tone Sampling
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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 audio amplifiers.
Innovation Solution
A calibration circuit is introduced that includes a tone generator, sampling circuits, and a gain adjustment mechanism to correct for gain variations in audio amplifiers, implemented on a semiconductor die or packaged module, which can be part of a wireless device with a digital audio path and an antenna for receiving wireless signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain calibration is performed to achieve high-fidelity audio reproduction, then audio quality is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent performs gain calibration during manufacturing or initialization before the device is used by the end user. The tone generator, sampling circuits, and gain adjustment circuitry are activated in advance to measure and correct gain variations across different audio frequency bands. This preliminary action ensures high-fidelity audio reproduction without requiring continuous calibration operations during normal use, thereby avoiding increased device complexity and power consumption.
2Measurement precision
If continuous calibration operations are performed to maintain audio quality, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic gain calibration operations rather than continuous calibration. The tone generator activates at scheduled intervals to perform calibration measurements across different audio frequency bands, and the gain adjustment circuitry applies corrections based on these periodic measurements. This periodic approach maintains audio quality while significantly reducing power consumption compared to continuous calibration operations.
Data Source
AI summary
In some embodiments, a calibration circuit for an audio amplification system can include a tone generator configured to provide a tone having a frequency to an input path of an audio amplifier, such that an input signal provided to the audio amplifier includes the tone, a a first sampling circuit configured to sample an output signal at an output node of the audio amplifier, and a second sampling circuit configured to sample the input signal at an input node of the audio amplifier. The calibration circuit can further include a gain adjustment circuit configured to generate a correction signal based on the sampled output signal and the sampled input signal to correct for a gain variation of the audio amplifier.