I'm designing the input/output impedance matching circuit for a RF power amplifier, based on the vendor supplied s2p file. I designed separately the input/output matching circuit at the given working frequency. But when I connect the input/output matching networks and the model based on the s2p file and do simulation in ADS, the matching frequency point went away from the designed frequency.
In the diagram, SnP is the model based on the s2p file, the left is the input network, the right is the output network. It seems the output network will change the S11. So the input matching network designed based no load no longer matching at the given frequency.
So, what's the correct way to do a matching based on the s2p file? Do I need matching them in order, that is, first output, then input?