By the way, the topic of third order intercept point is covered very
nicely in _Experimental Methods in RF Design_. As in its predecessor
_Solid State Design for the Radio Amateur_ (Hayward and DeMaw), the
authors point out that it's not always obvious whether the intercept is
at a circuit's input or output, and consequently the importance of
specifying which is meant. So in that book, you'll also find the more
obscure but unambiguous abbreviations IIP3 and OIP3.

Roy Lewallen, W7EL