Si53xx-RM

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

38.88MHz External XA-XB Reference

 

1200

 

 

 

 

 

1000

 

 

 

 

jitter, fs

800

 

 

 

 

600

 

 

 

 

RMS

400

 

 

 

 

 

 

 

 

 

 

200

 

 

 

 

 

0

 

 

 

 

 

155.51

155.515

155.52

155.525

155.53

Input Frequency (MHz)

Input Frequency Variation = ±50 ppm

Figure 85. ±50 ppm, 2 ppm Steps

162

Rev. 0.5

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Image 162
Silicon Laboratories SI5316 Test Conditions, Input Frequency Variation = ±50 ppm, MHz External XA-XB Reference, Jitter, fs