AFE7799: Uplink DC spur issue

Hi Expert

Upload our Latte txt file for reference.

4101.configCustom2_3749p70.txt

Hi expert,

Could you please have a look and provide some feedback? Also, customer is wondering if there any way and how to extract I/Q data through AFE for analysis?

Regards,

Allan

Hi,

At this point, it is not certain (since we have the whole system output at VSA) where this spur power level begins changing. Can you please capture the data at the FPGA as shown below and check if the spur is present? 

Can you please elaborate further what would like to achieve?

Thanks,

Serkan

Hi Serkan

Thanks for your comment.

We have done some tests according to your comment, the attached is one of the test results.

The picture is the spectrum of one symbol, the first 100 RBs in 100MHz operation band are utilized.

The .csv file is the ADC value of this symbol.

We can see there is a DC spur in the spectrum.

Our question is, is there any way to supress the DC spur more?

Thanks for your help

John

Adc.csv

Hi,

Is the below data in dBm or dBFs? Please confirm. Based on the data, there is at least 80dB difference and aligns with the datasheet values.

John Show said:

c.csv

Would you please check the data on the Fb as well?

Thanks,

Serkan

Hi Serkan

This figure is drawn by 10log(I^2 + Q^2). However, we tret all ADC values as integer, so it is conceptually dBm but not real power value. 

Does the "Fb" in your reply mean "feedback path"? If so, what is the impact of feedback path to Rx path?

Thanks for your help!

John