Anyone knows how AD8376 (SiGe) can get a 50dBm OIP3 ?

I am trying different amp topologies to get the similar number, but fail.

Topologies I tried:
Single NPN transistor with 100 mA current --> Bad wideband matching and bad IP3.
cascade two NPN transistor with 60 ro 100 mA current --> 40dBm OIP3.
Cascade a NFET on top of a NPN transistor with 100 mA current --> 33 dBm OIP3.

I am wondering what kind of topology or trick they use to achieve this high OIP3, do you have an idea ?

Thanks.

http://www.wikipatents.com/6218899.html

Just an aside, I notice you can get a pdf printout of most patents thru google. You go to www.google.com. Then in this case, in the search window type in "patent 6218899", without the " marks, and you get the patent for free and without needing a login.

Thanks a lot. This patent looks interesting but I don't like patent document: there is no real circuit setup, no simulation or measurement data. Just some claims.

I can see it uses a single npn as the core of the amp with some selectable loads at the source (degen) and drain (load). I am wondering how it can achieve wide band matching and why the OIP3 can be as high as 70dBm. I don't see the magic there.