English is not my mother tongue, probably I've been a bit unclear.
The graphic shows gamma_opt (marker 15) and the maximum gain match (the red circle, e.g. marker 13 and 14).
What confuses me is the red circle in the graphic I've posted. According to my simulations all input impedances on its line would give me the maximum gain of ~21,95dB. The gain can't be higher than this.
Usually I'd only expect a single point, which is s11*, to give me the maximum gain.
I've used exactly the same simulation setup for other amplifiers, and it always replied that specific s11* point within my simulation (so I suppose my simulation setup should be correct). Now here, when I implement the s2p file for the MGA71543, I get a circle of many different impedances, which are all resulting in maximum gain.
Now my question would be, can this circle be correct?
And if so, why is it a circle instead of a single point (s11*)?