Dual clock spread for low clock emissions with recovery

Abstract

A method and apparatus provides for the generation and recovery of a stable clock signal having harmonic emission suppressions using dual spread spectrum clock signals. The transmission frequencies of non-mixed, spread spectrum lower frequency clock signals may be varied and, upon receipt of these non-mixed signals, they are mixed into sum and difference signals. The sum signal thus generated is representative of the desired clock signal to be recovered. Such conditioning of the non-mixed signals need only occur within the receiver, thereby allow the channel that transmits the non-mixed lower frequency clock signals to the receiver to be lower bandwidth than would be required to carry the final, recovered, and higher frequency clock signal produced by the receiver.

1 . A structure for generation and recovery of a stable clock signal having harmonic emission suppressions using dual spread spectrum clock signals, comprising:
 first and second modulator elements that frequency modulate first and second lower frequency dual clock signals, respectively, to generate first and second modulated clock signals, respectively, that sweep in opposing directions with respect to one another in a spectrum of operation, wherein said first and second lower frequency dual clock signals are generated from a high frequency clock signal and have respective frequencies that are less than a frequency of the high frequency clock signal; and   first and second modulator elements that frequency modulate first and second lower frequency dual clock signals, respectively, to generate first and second modulated clock signals, respectively, that sweep in opposing directions with respect to one another in a spectrum of operation, wherein said first and second lower frequency dual clock signals are generated from a high frequency clock signal and have respective frequencies that are less than a frequency of the high frequency clock signal.