Really thank you for your help.
I am struggling with the application of AD8333.
I am confused that when I input 4*LO sine wave to Din of DS90C401, its output (Dout-, Dout+) was not a sine wave. Even though I adjust the amplitude of the input. It still could not work.
I don't how to solve this issue.
The purple trace with a sine wave is the input to Din of DS90C401，but the other two traces were Dout(+, -). I don't know why they were not sinewave.
Thanks for your kind help
Can you provide a schematic of your circuit? Do you have the transimpedance amplifiers on the outputs of the AD8333? See Figure 64 in the AD8333 datasheet as a reference.
I am very grateful for your kind reply. I actually followed the reference design of the AD8333 datasheet. I firstly simulated this circuit in Multism, but it seemed to have problems that are shown below.
As the figure above, I input a reference signal with 4MHz(sinewave) to 4LO directly, and I set Reset to a high level. RFIP and RFIN were a pair of differential signals which were converted by the previous VGA circuit. The output was as follows. In fact, It did not accomplish I/Q demodulation when I set Reset to High.
However, when I put Reset to a Low level. It seemed to work with 2Lo signal plus DC component, but its signal was definitely weird, like below.