Oscillation measurement of LNA

[huytergan]

I wanna measure LNA to see if there is oscillation or not with spectrum analyzer. How should I set up the measurement? Is the noise figure what I m looking for or the stability?

 

[BigBoss]

Check the Stability first with VNA then observe possible oscillation with SA by terminating the Input of the LNA.
Adjust SA's settings to able to see lowest signal level that will give you an opportunity to see small level oscillations. ( decrease RBW to min.)

 

[vfone]

Checking for instability of an LNA is not as simple as it looks. Even an LNA is designed to amplify very small signals, most of the RF systems in use today, cannot ignore large input level behavior.
The assumed 50ohms inp/out loads, it must be stable for all input power values, with instability occurring only due to mismatch effects.
In some cases, the mismatch effects may also affect the behavior of the LNA at frequencies where a steady–state solution exist.