Audio driver system and method
View Patent ↗An audio driver equipped with a distortion compensation unit corrects for detected distortion and includes a digital to analog converter (DAC), an amplifier, and an output driver that drives a loudspeaker. Between the output driver and the loudspeaker, the audio driver can include a series resistor and a differential amplifier to measure the voltage across the resistor. A distortion detection unit can use the detected voltage to determine whether distortion, such as rub and buzz distortion is present. The distortion detection unit can comprise an analog to digital converter (ADC) to digitize the voltage data, an FFT to transform the voltage data into frequency information, a root-mean-square (RMS) module that measures the energy at each frequency, and an analysis module which looks for the distortion signature in the energy spectrum.
1. An audio driver comprising:
a digital to analog converter (DAC) operable to convert a digital audio signal into an analog audio signal;
an amplifier operable to receive the analog audio signal and produce an amplified analog audio signal;
an output driver operable to drive a loudspeaker with the amplified analog audio signal;
a resistor placed in series between the output driver and the loudspeaker;
a differential amplifier operable to measure a voltage signal across the resistor;
an analog to digital converter (ADC) operable to digitize the voltage signal across the resistor;
an adaptive filter operable to approximate the digital audio signal and remove the digital audio signal from the output of the ADC, thereby producing a noise signal representing external sounds measured by the loudspeaker;
a noise canceller operable to generate a signal for cancelling the noise signal; and
a mixer operable to combine a source digital audio signal with the cancellation signal generated by the noise cancellation module and output the digital audio signal.