SI5317 Datasheet, PDF (34/50 Pages) Silicon Laboratories – Pin-Controlled 1_710 MHz Jitter Cleaning Clock

Si5317
5.1.4. Reference Clock Frequency
Based on the application and desired output frequency, care should be exercised in selecting the frequency on the
reference used for XA/XB. When the CKOUT operating frequency is close to having a simple integer relationship,
significant spurs can occur. For example, compare the spurs when the CKOUT operating frequency is 622.08 MHz
with a reference of 114.285 MHz (see Figure 22) versus a reference frequency of 38.88 MHz, which is 16 times the
XA/XB reference (see Figure 19).
Figure 19. Effect of Reference Frequency on Spurs
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Preliminary Rev. 0.15