Silicon Laboratories SI5323 Clock User Manual


 
Si53xx-RM
162 Rev. 0.5
APPENDIX G—NEAR INTEGER RATIOS
To provide more details and to provide boundaries with respect to the “Reference vs. Output Frequency” issue
described in Appendix B on page 121, the following study was performed and is presented below.
Test Conditions
XA/XB External Reference held constant at 38.88 MHz
Input frequency centered at 155.52 MHz, then scanned.
Scan Ranges and Resolutions:
± 50 ppm with 2 ppm steps
± 200 ppm with 10 ppm steps
± 2000 ppm with 50 ppm steps
Output frequency always exactly four times the input frequency
Centered at 622.08 MHz
Jitter values are RMS, integrated from 800 Hz to 80 MHz
Figure 85. ±50 ppm, 2 ppm Steps
38.88 MHz External XA-XB Reference
0
200
400
600
800
1000
1200
155.51 155.515 155.52 155.525 155.53
Input Frequency (MHz)
RMS jitter, fs
Input Frequency Variation = ±50 ppm