question about the CMOS LNA IC measurement

[wccheng]

LNA measurement

Dear all,

I have a question about the CMOS LNA IC measurement. I hope anyone could answer me. My idea is this: I will make an LNA + output buffer and standalone output buffer (this standalone output buffer is same as the one combined with LNA). I will measure the power gain and NF of the LNA + output buffer module first. Then I will measure the standalone output buffer power gain and NF. Then, I am back calculated in order to get the standalone LNA power gain and NF. Does this procedure correct?
Based on this procedure, I have another question. For the LNA + output buffer, the input of the buffer is loaded by the output of the LNA. If I measured standalone output buffer, it would be loaded by 50 ohms (from network anaylzer or signal generator). How could I calculate this effect in order to back calculated the standalone LNA performance?

Thanks

wccheng

 

[hhnn]

I am also having the same problem. Please help !

Thank

 

[mbyoussef]

In Friis equation the NF of the output buffer is referred to a source impedance = 50 Ω, so you don't need to worry about the difference in loading.