Using an External Clock with AD9081-FMCA-EBZ

Also.............you can not ignore Step 4 since providing the Ref Clock to the ADS9 is required for FPGA SERDES PLL to be phase lockd to SERDES PLL on the AD9081.

Please connect 750 MHz clock source to ADS9V2 ExtClk SMA connector.  Also........the frequency should be set to what the GUI display setting for "Tx Ref Clock" under CLOCK CONFIGURATION.

Step 4 is setting the analog input to the ADC, but also says to leave it off.  You're saying we still need to do that?

We are providing the 750MHz clock (see Step 4 in the OP), with External Direct Clocking chosen.  The Tx Reference Clock in the GUI is an un-editable field and appears to change based on other editable selections such as "Tx Data Rate"

These are the settings that we currently have:

With the settings shown..................Provide a 12 GHz, 13 dBm signal into the Ext Clk SMA on FMC board.

Provide a 375 MHz 4 dBm input into the ADS9V2 board Ext Clk SMA connector.

Hopefully that works.

I think the bigger issue is that when we select those settings, ACE throws a bunch of errors.  Unfortunately, the board requires modification and we can't wait to get this working so for now we are using the internal clock, as we were able to get that working.

Thank you for your assistance.. We will try your suggestions when we have time to go back to trying external clock sources.

OK.............but note that no further board modifications should be  required after installing C4D and C6D.  Anyways........glad to see that you still can progress with HMC7044 based clocking solution.

PMH Thank you for the help. I am a colleague of sdepot. When we run the FMC with the internal clock we are able to get a signal out, but we are also seeing several double sideband spurs. They are located at +/-50kHz, +/-297kHz, and +/-520kHz. have you seen these spurs, and what can we do to eliminate them?  

Hello,

For the JESD 375MHz clock, what kind of clock is the ADS9 looking for?  Square wave centered at 0, square wave with offset (so no negative voltage), sine wave centered at 0, other?

We noticed that when we hit the 12GHz with +13dBm that it results in more spurs apparently from overdriving it.  Would you suggest using a lower power input?  If so, what value?