3order intercept

can anyone explain 3-order intercept point in spectre simulation?
if frequence1 is 2.45GHz, frequence2 is 2.35GHz, then 1-order harmonic is 2.45GHz, 3-order harmonic is 2.65GHz?
could you explain it in detail?
because 3-order harmonic isn't exclusive, the IIP3 is different, which is the result i need?

thanks a lot!

Added after 3 minutes:

another question, what factor affect the IIP3, how can i improve it? eliminate the common source?
thanks

could anyone explain it for me?
thanks

maybe this help you:

http://www4.tpgi.com.au/users/ldbutl...modulation.htm

I like this one:

http://www.procom-dk.com/techinfo/e0...tion-concepts2