This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS52J90: Strange spectrum signature on acquisitions at 25 MS/s

Part Number: ADS52J90

Dear support team,

I am developping and testing for a customer a new 32 analog inputs FMC board, which has 2 ADSJ90 on it. The board is plugged on a carrier, where the FPGA controling the acquisition lies.

The prototypes are running as expected, except that sometimes, I see a strange spectrum signature on all channels. This happen for acquisitions at 25 MSa/s and fin = 10 MHz (in reallity 9.99794006347656 MHz) . Attached is a FFT plot issued from HSDC Pro and the corresponding ADC data. There are 2 "frequency square", are the left side of the 5 and 10 MHz lines. The ADC is running in 14-bit mode, with zero padding to 16-bit.

Could your ADC expert have an idea of what could produce this strange spectrum signature? It seems to be a "digital/logic" problem. It would help a lot.

Kind regard, Jean-Luc

CHC_data0.txt 

CHC_0_fft_sreenshot.png