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AD9364 VDD1P3_BB Power supply

Question asked by Raveendra on Dec 19, 2014
Latest reply on Dec 19, 2014 by Raveendra

Hi all,

 

I designed a custom board with AD9364 with Artix FPGA. I am facing a facing a problem with 1.3 V Supply section, I checked the power supply section individually, it is working fine. Let me explain my power supply scheme, i am using 3.3 V from externally, this 3.3V converted to 1.8V by using Analog devices ADP2164, and this 1.8V converted to 1.3V by using 2nos ADP1755 regulators. One regulator for few sections of AD9364, another one for few section of AD9364 ( same as power supply like AD-FMCOMMS2/3/4). I attached my schematic for reference. 1st regulator (U13) section is working fine and it is generating 1.3 V individually and even when i connected that to further AD9361 it is showing 1.3V only, the problem is with 2nd regulator section (U15), it is working individually (means when i didn't connect this section to AD9364) and showing 1.3 V, when i connect this 1.3 V to VDDA_BB (pin K4 of AD9364), the voltage is increased to 1.8 V. when i connect to only this net, the voltage showing to 1.8 V.  When i remove the connection (Removing FB9 Bead) and voltage is coming back to 1.3V.

Please help out why this is happening when i fed voltage to VDDA_BB (K4) pin?  If i didn't connect voltage to this pin, what are all impacts of AD9361 functionality.

Below are all my 9361 voltage levels set in my customized board.

VDDA: 1.3V

VDD_INTERFACE: 2.5 V

VDDA_GPO: 2.5 V.

I attached my schematic of power supply section and transceiver section.

 

Thanks,

Raveendra

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