I have setup a circuit according to page 15 of AD811 Op-Amp datasheet . The design receives 0.5-1.2 vpp sine wave between 1Hz-50MHz from AD9850 DDS and it also has around +0.7 to +1 v offset voltage.
According to the schematic below, I have set VG- to Ground, VG+ to 0-1.3v ( the clipping voltage of AD834) and the signal goes to VIN. When I directly connect the signal with the DC offset voltage, everything goes well but no output is seen when I put a coupling capacitor = 100nF between the VIN and the signal to remove the DC part (Cin in the design).
As I read in AD834 datasheet , its output is set by (X1-X2)(Y1-Y2)x4mA and I have not seen limitations for AC signals around the ground.
In fact I want to have a pre-amplification phase with gain=x2 before this design and I need to send its signal without the DC part to this schematic to get rid of clipping to upper voltage region (VS+).
Why this design does not accept signals without offset?
EDITION: the pre-amp: