Hi BigBoss,
Right, well the topic I'm covering in my course is oscillators, but this is three-port networks and trying to switch the reference terminal and adding feedback to increase instability. I've attached the question that I'm trying to solve, my schematic and data display.
I've added a inductive feedback of 398 nH, then my |S22| after doing the transformation is 1, which I couldn't
figure out how to explain. Now I did all the calculations in MATHCAD, where the value is 1.0001576518877 using 13 decimal places! Showing that S22 is greater than 1, which would indicate that everything outside the circle is unstable, whereas there's more instability on the output without the feedback. So I'm just confused how to interpret the stability circle on the output, i.e. take it greater than 1 or less than 1, unless there's a definition out there for a magnitude of 1.
As another example question in my notes indicates that there should be increased instability after adding the feedback, but in this case S22 it doesn't?