| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a spread spectrum clock generating circuit capable of providing a frequency modulation clock of a desired moderation degree even when the manufacturing variation, power source voltage, operation temperature, and operation frequency vary. <P>SOLUTION: The spread spectrum clock generating circuit comprises a first delay control type oscillation circuit 104 for variably controlling the oscillation cycle at a control cycle interval according to a control signal, a clock signal fo1 obtained by dividing an output of the first delay control type oscillation circuit, a control circuit 103 for outputting a frequency control signal C based on a phase comparison result, a modulation maximum determining circuit 106 for determining the modulation maximum A, a modulate signal generating circuit 107 for generating a modulation control signalαin the modulation maximum A, and a second delay control type oscillation circuit 108 for variably controlling the oscillation cycle of an output clock signal at the control cycle interval according to the control signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
