Patent ID: 8525710

Claim:
An electronic audio device, comprising: an audio output for providing an audio output signal to an external device, wherein the audio output signal has a DC offset; a digital-to-analog converter for converting digital input values to an analog signal at an output of the digital-to-analog converter, wherein the audio output is generated from the output of the digital-to-analog converter; an audio output monitor having an input coupled to the audio output signal; a comparison circuit for comparing an output of the audio output monitor with the digital input values to generate error values indicative of a DC offset of the audio output signal from a comparison of first transitions in the output of the audio output monitor with second transitions in the digital input values, wherein the comparison circuit includes a hold function, and wherein the comparison circuit determines the value of the DC offset during a measurement interval and holds the output of the comparison circuit after the measurement interval, whereby continuous changes in the DC offset caused by changes in the output of the comparison circuit are avoided, and wherein the comparison circuit further comprises a timer that triggers the measurement interval at periods of greater than 50 milliseconds; and a combining circuit for adjusting the digital input values in conformity with the error values to reduce the DC offset of the audio output signal.