AnsweredAssumed Answered

Is my ADC AD9680-500 inputs broken?

Question asked by Chris449 on Apr 13, 2017
Latest reply on Apr 13, 2017 by UmeshJ

Hello all,

I built a zeros IF receiver using the IQ demod ADL5380 + VGA ADL5202 + ADC AD9680. I am using your DAQ2 fpga design 2016R2 (ZC706) to receive the signal from both ADC. I designed a simple matlab GUI for further signal processing. All the JESD test are okay, I can also receive the test signal from ADC.

So I tried with a RF generator and drive the receiver and be able to receive a 30.72MHz CW (complex signal) at the adc.

So,up to the ADC input, the signals are correct.

Below is the spectrum that I received after nulling the image and the LO.

I can observe that:

   1- noise level is very high

   2- I am close to the ADC saturation level while the ADC input signal (on the ADC pin) is very small (voltage swing > 100mV compared to the 2.06Vpp ). I configured the ADC input impedance to 200Ohm.




Before making a new board and because of 2), I am thinking that the inputs are broken (I checked the different power supply).

How could I confirm that I am correct or do you see something to check?

Thanks for your help.