US Patent 7750713 Spread spectrum clock generator

A spread spectrum clock generator for sequentially modulating a source clock of a fixed frequency with a predetermined frequency range, including: a plurality of first loading units configured to delay clock edges of the source clock by a delay time corresponding to the number of unit delay steps determined by delay step control signals, wherein each of the first loading units comprises a plurality of second loading units each of which is configured to vary a delay value of each unit delay step by changing an inner interconnection configuration thereof in response to unit delay step control signals.