Patent ID: 7679464

Claim:
An apparatus for frequency modulating a pulse width modulated signal, including: a first oscillator component having a first bi-directional charge pump with an output connected to hysteresis comparator means, a first feedback loop connecting the output of said hysteresis comparator means to an input of said first bi-directional charge pump, said output of said hysteresis comparator means comprising a pulse width modulated signal; a second oscillator component connected to an input of said first bi-directional charge pump, a second feedback loop connected from said output of said hysteresis comparator means to an input of said second oscillator component, whereby said second oscillator component is arranged to generate a spread spectrum modulation signal that drives said first oscillator component to generate a spread spectrum, frequency modulated pulse width modulated output; wherein said second oscillator component includes a second bi-directional charge pump having an output connected to said first bi-directional charge pump as an oscillator bias current.