I have designed a DAQ borad including AD9764, AD6644 and it communicates with Xilinx Spartan 3AN FPGA through FX2 expansion connector.
As indicated in the attachments we can see the input&output connections and the clock signal (which is RC filtered version of Clockin at 16MHz coming from the FPGA) . I am wondering why i am getting the same voltages at the IOUTA and OUTB nodes at the AD9764 output (simply 0 or 20mV at the output of AD9631 opamp ) although I apply the code "00000001111111" from the FPGA. I checked the DAC inputs and see that they are as the FPGA output. Is it about the AD9764 or the AD9631 opamp or the noise level?
I will appreciate any help .
Thank you very much