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Honored Contributor
Honored ContributorPhase modulation
The attached picture shows phase modulation of a clear clock by a sinusoidal signal. Would you plz help me figure out what kind of circuit does this? I know there r generators that can generate ...
Altera_ForumHonored Contributor
Honored ContributorHi,
The sin(2*pi*fc*t) indicates the fundamental sinusoid component of the clock signal. This is a standard equation and the 2*pi allows the sine values to cycle around... The picture explains a clean clock jitter on the basis of two sinusoid phase modulation. You can see there is a clear relationship between clock jitter and the amplitude of the modulating sinusoid. In the digital domain you can reproduce that in a DDS circuit(Direct Digital Synthesiser) by generating the clock "sinusoid" component according to word value decided by a lut containing one cycle of the modulating sinusoid amplitude values). edit: alternatively, use altera NCO and set to phase modulation then pass the phase modulation value as variable input from the LUT. (altera NCO is an implementation type of DDS) Kaz
