AD9208 vcm export


I would like to connect a DC coupled signal to AD9208, and I would like to connect a VCM signal to my opamp buffer. (i'm using AD9208-3000EBZ board with differential inputs)

I went with the procedure described on page 26 of AD9208 "Input Common Mode" and on the Vref pin the 1.9V voltage occurred.

there is 1.9V for reg 0x18e3 =  0x5e and 1.8V for reg 0x18e3 = 0x40, but never expected 1.35V. I was also able to output the diode signal 1xdiode =0.58V and 20xdiode = 0.67V, so I suppose that the Vref output is functioning and none of the external components (multimeter?) are affecting the pin.

I have seen several similar issues described on the forum with similar or same chip:


but the VCM issue was never resolved.

Please help, anybody who have managed to get the VCM voltage exported.

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