7. Given that the base of the quadrilateral pyramid $S-ABCD$ is a square with side length 2, $SD \perp$ plane $ABCD$, and $SD=AB$. Then the surface area of the circumscribed sphere of the quadrilateral pyramid $S-ABCD$ is $\qquad$
$$
\text { II, } 7.12 \pi \text {. }
$$

According to the problem, the radius of the circumscribed sphere of the quadrilateral pyramid $S-ABCD$ is $R=\sqrt{3}$.
Therefore, the required surface area is $4 \pi R^{2}=12 \pi$.