ADC12DL3200: (Fs/4 +/- Fin) spur issue

re-post the picture.  

Hi,

Could you send us the raw data in a .csv file so that we can examine it and find the issue?

Thanks,

David Chaparro

f800m.csv

Hi

thanks for quickly response.

enclosed the raw .csv which export from vivado. the column A~AF corresponding to sample 1~32 and so forth.

hi

BTW, i set this ADC sample format in offset binary mode(reg 0x204 = 0x8).

Hi david,

enclosed the .csv raw data and my matlab FFT code in .rar, thanks for your kindly support~

2260.Analysis.rar0880.f800m.csv

thanks for check my raw data file, i've posted on last reply.

Hi Sir,

Can i get any response? really need help to move on the right way forward...

David Chaparro said:

Hi,

After looking at the data the you sent it looks like a problem is occurring when the FPGA is taking the data from all the LVDS lines and putting it together. Can you check your code and make sure the FPGA is capturing the data following the datasheet recommendation, Figure 5 on page 34 might be of assistance.

Regards,

David Chaparro

Hi David,

yes i followed the datasheet page 33, figure-6 to organize the sampling data. in this 6GSPS DES mode, all the LVDS lanes been used, so that i could get a 1024*32 data matrix exporting from vivado.

1024 is the length setting in vivado, and 32 is the deserializing factor that (6GHz sampling clk/187.5MHz app_clk = 32). then i do the FFT in wave vision as below:

1)  import the 1024*32 sample data into wave vision. 

2) just select only one channel, i could get the right FFT single tone. as below first picture shown.

3) if i select more than one channel, for instance, i select 4 channels, i will get (Fs/4 +- Fin and Fs/2 +- Fin) tones. as last picture shown.

Is this reasonable and why?

result of selecting single-channel:

result of selecting multi-channel:

could you have a little more explaining on this phenomenon? thanks a lot.