AFE7799: how to reduce spur

HI expert,

The spur is at the center frequency, it could be a DC leakage inside the 7799.

BRs,

Adis

Hi,

What is the configuration for the AFE? Since you mentioned it is at center, it looks like Lo leakage.

Can you share the lowIF parameters in your config?

Thanks,

Serkan

Hi Serkan,

Which registers is thess lowIF parameters on?

BRs,

Adis

Hi,

In the beginning of .hex file, you should see parameters as commented.

Thanks,

Serkan

Hi Serkan,

Could you help to review the config directly.

Thanks.

BRs,

Adis

configCustom2_3625P14_chiang_20240108.txt

Hi Expert

Is there any comment on that?

Thanks!

John

Hi Expert

We have done some tests on adding fixed offset to the I/Q data received from AFE7799 to evaluate if there is any DC bias voltage on the receiver. The result shows, whether we add positive or negative values, the DC spur becomes worth. It seems the spur is not introduced by DC bias. Do you have any comment on this?

Thanks!

John  

Hi Serkan

Thanks for your reply. May I ask what does "ulChan" stand for?

Could you please also give us an example? Assuming our data rate is 368.64M.

Many thanks!

John

ulChan is for UpLink(Rx) Channel 0-3(Rx1-4).

Assuming you have one AFE on your board and using RX1. Please use the indicated column for the 368.64 rate. rxOutputDataRate must be in MHz and dcFilterBw must be in Hz.

rxDcBw(0, 0, double rxOutputDataRate, double dcFilterBw)

Thanks

Hi Serkan

We have tried this API function, but got less improvement on the DC spur.

Do you have any other suggestion, or hint for debugging this?

We saw the DC offset can be reduced to at most -88dBFS in the data sheet, how can we achieve that?

Thanks for your help.