AnsweredAssumed Answered

About AD9914 FSK deviation

Question asked by kenton.chu@anstek.com.tw on Mar 4, 2015
Latest reply on Mar 15, 2015 by LouijieC

Dear Sir,

 

For our application needs to fixed the deviation while FSK mode. But, I found the below result on our board if any ignore ? Or how to get we want ? Thanks.

 

1. Fixed the reference Clock @ 3.5GHz -5dBm by ADF4350 as below. And triangle FSK modulation signal (Freq=76KHz, 2.5Vp-p) on Vtune(pin 20).

pic1.jpg

2.Measure from C106 as below, deviation is 16.4MHz.

C106.jpg

3. AD9914 fixed  output freq at 144MHz ,result as below.Deviation is 488KHz.

144M.jpg

4. Fix output frequency at 430MHz as below.Deviation is 1.83MHz.

430M.jpg

In sum, the deviation is changed while AD9914 output frequency modification.

Outcomes