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Hi. I designed an S band LNA and fabricated it but there is a little problem. S11 and S22 of the circuit is nowhere near the simulation
Here is the both measurement and simulation results. What could be the problem here ?
yes, there are big electrical lengths at the input and output, and your device impedances are rotating all over the place as the frequency changes. You need to make a measurement, or a simulation, right at the terminals of the device to get the expected smith chart refleciton corefficiens.
You can tell that you have long FIFTY OHM transmission lines in the circuit as the circles are centered at the middle of the smith chart.