Determine the M and D Values

UltraScale Architecture Clocking Resources User Guide (UG572)

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1.10.2 English

Determining the input frequency can result in several possible M and D values. The next step is to determine the optimum M and D values. The starting M value is first determined. This is based off the VCO target frequency, the ideal operating frequency of the VCO.

Equation 3-10 ug572_c3_Clock_Management00049.jpg

The goal is to find the M value closest to the ideal operating point of the VCO. The minimum D value is used to start the process. The goal is to make D and M values as small as possible while keeping ¦ VCO as high as possible.