DAC Calibration Circuit for Reference Voltage Drift in Audio Amplifiers

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Solution Overview

Problem

Existing audio amplifier circuits in wearable devices face challenges in achieving high-fidelity audio reproduction while operating in a power-efficient manner, particularly due to variations in reference voltages affecting the performance of digital-to-analog converters (DACs).

Innovation Solution

A calibration circuit is introduced that includes a first circuit generating an output voltage based on a reference voltage and a second circuit comparing this output voltage with another reference voltage. The calibration block adjusts the first circuit to compensate for changes in the reference voltage, ensuring accurate voltage provision to bit cells within the DAC.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a digital-to-analog converter (DAC) is used in an audio amplifier circuit, then audio signal conversion capability is improved, but sensitivity to reference voltage variations worsens

Engineering Contradiction:

Improveaudio signal conversion accuracyVSAvoidperformance stability under reference voltage variations

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the output of the second circuit (comparing reference voltages) is fed back to adjust the first circuit generating the output voltage. This closed-loop feedback system continuously monitors reference voltage variations and compensates for them, thereby maintaining stable DAC performance despite reference voltage fluctuations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The calibration block dynamically adjusts electrical parameters (voltage levels) of the first circuit based on the comparison results from the second circuit. By changing these parameters in response to reference voltage variations, the system compensates for drift and maintains accurate audio signal conversion.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If high-fidelity audio reproduction is pursued, then audio quality is improved, but power consumption worsens

Engineering Contradiction:

Improveaudio reproduction fidelityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The calibration circuit performs preliminary adjustment of the DAC's reference voltage before actual audio conversion operations. By pre-compensating for reference voltage variations through the calibration block and comparison circuit, the system ensures high-fidelity audio reproduction without requiring continuous high-power operation during normal audio processing.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12301246B2Digital-to-analog converter calibration for audio amplifiers

Publication Date: 2025.05.13 SKYWORKS SOLUTIONS INC

AI summary

In some embodiments, a calibration circuit can include a first circuit configured to generate a first output voltage based on a first reference voltage, and a second circuit configured to compare the first output voltage and a second reference voltage. The calibration circuit can further include a calibration block configured to provide an adjustment to the first circuit based on the comparison of the first output voltage and the second reference voltage, with the adjustment being configured to compensate for a change in the first reference voltage. In some embodiments, such a calibration circuit can be utilized for and/or be a part of a digital-to-analog converter for wireless audio applications.