Patent ID: 6658043
Filing Date: 2003-12-02
Classification: H03L,H04B

Abstract:
A method for controlling a plurality of spread spectrum clock generator circuits, said method comprising:(a) providing a first spread spectrum clock generator circuit and a second spread spectrum clock generator circuit, and providing a synchronization control logic circuit; (b) controlling said first spread spectrum clock generator circuit so that it outputs a first predetermined plurality of frequencies over a first predetermined time period, as according to a first predetermined spread spectrum profile; (c) controlling said second spread spectrum clock generator circuit so that it outputs a second predetermined plurality of frequencies over a second predetermined time period, as according to a second predetermined spread spectrum profile; and (d) further controlling said second spread spectrum clock generator circuit so that its second predetermined plurality of frequencies at least partially overlaps the first predetermined plurality of frequencies of said first spread spectrum clock generator circuit, while at the same time controlling a frequency difference between the outputs of both said first and second spread spectrum clock generator circuits so that an overall increase in electromagnetic emissions due to a combination of said first and second spread spectrum clock generator circuits is less than 6 dB above the electromagnetic emissions due solely to said first spread spectrum clock generator circuit.