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Unused VDD_GPO

Question asked by rgetz Employee on Jul 7, 2016
Latest reply on Jul 14, 2016 by Vinod

It's clear from the datasheet, and the discussion at:

How do I power the AD9361?¶

 

That when I'm not using the AUX ADC/DAC or GPO signals - I need to connect 1.3V to the VDD_GPO pin. My question is which one?

 

On the FMCOMMS2/3

https://wiki.analog.com/_media/resources/eval/user-guides/ad-fmcomms2-ebz/fmcomms2_reve.pdf 

 

There are multiple 1.3V nets, which are somewhat isolated in the layout to provide best performance. It would be easy to take ball B8 (VDD_GPO) and bridge it to ball B9 (VDDA1P3_ TX_LO), but I don't want to cause issues on the TX_LO. (better said - I don't want to waste time tracking down RF artifacts if someone knows I should/shouldn't be doing something).

 

Am I better taking it from one of the other nets? (VDDD1P3_ DIG, on Ball F12), or if I am better necking another route (separately) down to ball B8 (VDD_GPO)?

 

Any insight based on past experiences would be appreciated.

 

Thanks

-Robin

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