| 摘要 |
Disclosed is a method and class D amplifier circuitry for compensating a pulse width modulated (PWM) signal. The method includes steps of generating a PWM signal for application to a driver stage; obtaining a filtered difference between the PWM signal and a version of the same PWM signal after the driver stage; generating a correction signal that is indicative of a sign of the filtered difference; and using the correction signal for adjusting at least one of the leading edge or the trailing edge of the PWM signal so as to compensate the version of the same PWM signal after the driver stage. The steps of obtaining and generating include steps of RC filtering, digital comparison and digital filtering. In the preferred embodiment the step of generating generates a one-bit correction signal. The correction signal is used to compensate the version of the same PWM signal after the driver stage for driver stage non-linearities and for power supply noise and variations. The PWM signal is preferably in a thermometer format, although other formats can be used, and the step of adjusting includes initial steps of combining two successive samples into one longer sample, and interpolating the longer sample by a factor in a range of about two to eight. In the presently preferred embodiment the step of generating generates the PWM signal from a multi-bit signal output from a sigma-delta modulator, where the multi-bit signal has 2n quantization levels, where n is in a range of about two to about eight.
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