Question
I would to enlarge the frequency operating range up to 8.5GHz
1. Is it recommended by you even the device is up to 8GHz(refer to datasheet)
2. The influence on the electrical performance.
Answer
Operation at 8.5 GHz is possible.
The gain stages of the AD8318 start to fail above 10.5GHz.
Note that parasitics of the evaluation board, as well as the package,
contribute to this performance decay.