measure Zin of an cascode LNA from S parameters

[anhnha]

I want to measure Zin of an cascode LNA using Cadence.
I am wondering if this is correct.
1. Measure S - parameters
2. Convert S to Z parameters
3. Zin = Z11 from the result above

I know that Zin is not Z11 in ZP analysis, though.

 

[BigBoss]

Just s-parameters are enough.

Zin\[\neq\]Z₁₁

Z₁₁ is "Input Impedance while the other ports are open"..
In order to see the right input Impedance, put you marker on the smith chart as " S₁₁impedance" that's it..

 

[anhnha]

Thanks. I think you misunderstood my post a bit.
My procedure is as follows:
1. Get S11 from SP analysis
2. Convert S11 obtained above to impedance, let's call it Z
3. Input impedance, Zin = Z