AD9516-1 issue

Hi,

Can you please clarify what you mean by the frequency shakes?  How do you have the LVPECL outputs terminated into your spectrum analyzer?  Can you read that the PLL is locked by monitoring the LD pin (0x0A1[5:0]=0)?  The loop filter components on the AD9789 evaluation board look fine for this configuration.

I would make sure that your reference frequency is stable.  If the reference input to the AD9516 is modulating, the PLL will try to track this modulation.

Regards,
Kyle

HI Kyle

Looking at photos of the frequency curve in 10KHz seem to modulation.

The reference input is used signal generator. not modulation.

The LD pin setting is 0x0A1=00.

Hi,

With register 0x0A1 = 00 you should be able to see a stable high (~3.3V) output on the LD pin.  The spectrum plot shows spurs at even intervals surrounding the carrier.  Lets see if we can find the source of these.

• At what frequencies are the spurs that are shown surrounding the carrier signal?
  • Is there anything running on your board at these frequencies?) 
• Do you have any other outputs running on the AD9516?
• Can you provide an image of the spectrum of your reference input?

Regards,
Kyle

HI.

I solved problem this time.

Reference input was the problem.

In the meantime, thank you.

This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

Thank you,
EZ Admin