What instrument should I use to measure IIP3 of a LNA?

Hi,

May i know what the instrument i can use to measure IIP3 of a LNA? The operating frequency of the LNA is 2.4GHz.

Regards,
Chun Lee

hi
use spectrum analyzer
regards

You need two signal generators and one spectrum analyzer. Connect the two generators input by a combiner to the LNA input. Send the two tones at, for example, 2.4GHz (f1) and 2.41 GHz (f2), same power, and see the signal at 2.39 GHz (2*f1-f2) and at 2.42 GHz (2*f2-f1). Measure the difference level between f1 and the armonic (or f2 and armonic), called IM3. The relaptions that link the IM3 and the IIP3 is: IIP3 = input signal level + IM3/2.
There are also the network analyzer of last generation can do the IIP3 linearity measurement directly.

By

When you first combine the two signals from the signal generators, make sure the IP3 generated by the signal generators is lower then the LNA's. If not, the you will need to use isolators after each signal generator so that they don't distort each-other.

Thanks for your kindly reply. I get it.