Patent ID: 7209064

Claim:
A method of spreading a spectrum of harmonic frequencies in a PWM output signal, the method comprising: receiving an input signal representing one of N quantization levels of a delta sigma modulator, wherein N is an integer greater than or equal to two (2); selecting a first pulse width modulator (PWM) pattern associated with the quantization level from a group of K PWM patterns, wherein: K is an integer greater than or equal to two (2); and the PWM patterns have discrete time slots during which a pulse can rise and fall; selecting a second PWM pattern associated with the quantization level from the group of K patterns, wherein selection of the second PWM pattern causes a rising edge of the second PWM pattern to shift in time at least two discrete time slots relative to a rising edge of the first PWM pattern to spread the spectrum of harmonic frequencies in the PWM output signal; generating a frame of the PWM output signal with the selected PWM pattern; and providing the PWM output signal to an amplifier.