Hi Frank, you have received valuable explaination on IP3 (IIP3 or OIP3).
To give you an idea on IMD there is a very interesting project that have demonstrated how passive components can limit IIP3 of a receiver. The project is the CDG2000 transceiver presented to the amateur radio world by Dave Roberts G8KBB, George Fare G3OGQ and Colin Horrabin G3SBI and published in RadCom (RSGB). The CDG2000 receiver presents an IIP3 of around +40dBm limited by the input coils and transformers, not only PIN diodes, mixers, amplifiers, filters (LC and Xtal). Maybe with new switches for the H-Mode Mixer and more performing LC BPF we may see front-ends reaching and going over IIP3 of +50dBm. 73 Gian I7SWX
