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AD9375 ORx to Tx loopback EVM issue

Category: Software
Software Version: 2019R2

Hi AD,

In my custom board I am interfacing AD9375 with Zynq Ultrascale plus MPSoC (XCZU11EG-ffvc1156).
I am using version of HDL code and No-OS application.

I am doing ORx to Tx loopback in RTL 

Tx sampling rate : 245.76MSPS

ORx sampling rate : 245.76MSPS

From VSG I am feeding QPSK modulated signal at ORx input and monitoring the Tx output in VSA, QPSK constellation, spectrum are perfect and EVM is 3-4% in VSA for QPSK symbol rates between 1Msymb and 8Msymb, 

But when I increase symbol rate beyond 8Msymb my constellation is not proper and EVM is dropping to 11-14%.

Do I need to change any filter configurations when my symbol rate is above 8Msymb, please suggest me how to proceed further.



  • What is your application? Why do you want to do a loopback from ORX to TX?

    Note that ORX path was mainly meant to be used for DPD applications.

    ORX path  should not be used as RX path  as there are certain limitations for the ORX path. ORX path is used for running TX tracking callibrations. Tracking calibrations cannot run if time is not allocated for Tx cals, which will degrade the TX performance.

    Refer below link:

     Purpose of "Observation Receiver"