question about S21 S22 in LNA

[ksit]

Hi, everyone.

This is my first time trying to design a wideband LNA from 3.1G~ 10.6G Hz. Up to now, i have a current mirror and a cascaded circuit with feedback circuit. I played around with the current , and don't understand why S22 is changing when i varied the current?

second question is, i cant get desirable S22 which i want it to be below -10db , and S21 , somehow, is a negative number.

can anyone answer my question.
THanks

 

[hanif]

check following links for your problem


S11 and S21 parameters for LNA design




Low-Noise Amplifier Stability Concept to Practical Considerations

**broken link removed**


what is the importance of S22 in an LNA??




how to broaden peaks of s11 and s22 in lna design