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Wrong response in ADF4360-0

Hi. I´m trying to do a circuit that generates signals with frequencies between 2.4GHz and 2.725GHz. I´m using ADF4360-0.   Sometimes, the out frequency is right. It has no noise (figure 1).

But, in other cases, the out frequency is wrong. It has noise (figure 2).

What can I do for better the circuit? Must the filter, voltage sources (AVdd, DVdd), reference oscillator and the rest of components be as close as possible  of the ADF 4360-0?

I used grounded coplaner traces with a characteristic impedance of 50 ohmns (figure 3).

Best Regards.

  • As you show in fig.2 , your PLL is not locked!!!
    So, try to recalculate your PIF (feedback filter). Use ADIsimPLL - nice program!!!
    Best regards!!!

    Alexius.

  • Hi, Edel!

    Of course, filtering components (C; L) will be as close as possible  to the ADF 4360-0  and will be replaced.

    Look at this: http://www.analog.com/static/imported-files/user_guides/UG-095.pdf

    Output traces will be straight chain as possible.

    Pin lenght may be shorter on footprint  ADF 4360-0.

    Best regards!

  • Hi, Georgy.Thanks for answer me.What do you mean with " (C; L)  "?I forgot to show my filter. My filter is in this archive.

    Best Regards.

  • Hi, Alexius.Thanks for answer me.I forgot to show my filter. For to create it, I used ADISimPLL. My filter is in this archive.

    Best Regards.

  • Hi, Edel!

    File in archive I can no open. It is no graphic picture. So I mean with  (C; L) with connection to pins 2; 21; 6; 4; 5.

    It important place L & C as close, as possible to pins. Look as placed this at evaluation board !

    Best regards!

  • Hi Georgy,In this archive, I show the filter. I hope that you could open it. Best Regards.

    Date: Mon, 10 Feb 2014 06:09:31 -0500

    From: analogvm-admin@analog-vm.hosted.jivesoftware.com

    To: hernandezes17@hotmail.com

    Subject: New message: "Wrong response in ADF4360-0"

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        Re: Wrong response in ADF4360-0

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    Hi, Edel!

    File in archive I can no open. It is no graphic picture. So I mean with  (C; L) with connection to pins 2; 21; 6; 4; 5.

    It important place L & C as close, as possible to pins. Look as placed this at evaluation board !

    Best regards!

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  • Hi, Edel!

      It seems that filter is right.  Q filter about require any time.

    I see out of range 2.725 GHz generation, it may be as result  departure from recomended "PCB DESIGN GUIDELINES FOR CHIP" in datasheet 

    PSB design will be changed, It is very important and caprice with Gigagerts project.

    Best regards!

  • Hi Georgy.

    I was Reading thes section "PCB DESIGN GUIDELINES FOR CHIP" and I think that I have to put Vias en the termal pad for to better the functionally of ADF 4360-0.  What do you mean with "I see out of range 2.725 GHz generation"? Are my grounded coplaner traces Wrong?

    Best Regards.

  • Hi languer,Thanks for answer me.

    That picture shows only one part of the top of my PCB. Those Green things are ground vías. The bottom of PCB is ground. 

    In next archives, I show the top and bottom of PCB.

    Best regards.

  • How is your grounding on the chip? I can only see the 7 green things on the picture; which I'm hoping are not representative of the ground vias.