Patent ID: 7161970
Filing Date: 2007-01-09
Classification: H03L,H04B

Abstract:
1. An architecture for a spread spectrum clock generator with reduced amplitude electromagnetic interference harmonics, said architecture comprising: clock pulse generating means including closed-loop voltage-controlled oscillator means for generating a series of clock pulses, said closed-loop voltage-controlled oscillator means further comprising a first V-to-I converter means converting voltage to current, said voltage-controlled oscillator means producing non-spread spectrum voltage-controlled oscillations; an open-loop voltage-controlled oscillator means coupled to said clock pulse generating means, said open-loop voltage-controlled oscillator means comprising a second V-to-I converter means converting voltage to current, said open-loop oscillator means producing spread spectrum voltage-controlled oscillations with reduced amplitude electromagnetic interference harmonics; first spread spectrum modulating means coupled to said clock pulse generating means for modulating said open-loop voltage-controlled oscillator means, said first spread spectrum modulating means comprising spread method means for generating a center and down spread selection—for modulating said open-loop voltage-controlled oscillator means, wherein said first spread spectrum modulating means comprises first programmable current mirror means and a first post-programmable current divider means to provide a current to produce said spread method means for said open-loop voltage-controlled oscillator means; and second spread spectrum modulating means coupled to said clock pulse generating means for modulating said open-loop voltage-controlled oscillator means, said second spread spectrum modulating means comprising frequency modulating means for frequency modulating said open-loop voltage-controlled oscillator means, said frequency modulating means comprising profile modulating means for modulating said open-loop voltage-controlled oscillator means and spread spectrum ratio generating means for generating modulation ratios for said open-loop voltage-controlled oscillator means.