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Q&A Measuring Input/Output Impedance with a VNA

On paper you can measure the input impedance of an amplifier circuit by attaching a voltage source to the input, shorting the output, and calculating the resulting impedance from the voltage and cu...

1 answer  ·  posted 3y ago by jm567‭  ·  last activity 3y ago by coquelicot‭

Question VNA Impedance
#1: Initial revision by user avatar jm567‭ · 2021-02-25T17:10:38Z (over 3 years ago)
Measuring Input/Output Impedance with a VNA
On paper you can measure the input impedance of an amplifier circuit by attaching a voltage source to the input, shorting the output, and calculating the resulting impedance from the voltage and current, or vice versa to find output impedance.  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;But how would I measure the Input/Output impedance of the amplifiers in the pictures below using a VNA? Do I just connect the VNA to the input, attach a short sma connector to the output, and then observe the smith chart? I don't want to destroy my instruments that's why I'm asking. Thanks.

![LNAs](https://electrical.codidact.com/uploads/dyJZnKTDFV4DRHpCzsJEBVQR)