transistor to be used for high IP3

What qualities within an NPN transistor makes good IP3 (low intermod distortion)?

I understand the rule of thumb, P1dB + 10dB but for wide band applications there appears to be some transistors that do better than others.

tnx

First criteria getting higher IP3 is the power handling of the transistor. Small, medium and high power transistors, each of them have different IP3?s. Higher the power, higher the IP3.
P1dB + 10dB rule depends by other factors, as bias impedance filtering.

Vfone,

I agree with what you say. IP3 does depend on tuning and biasing method.

>> Small, medium and high power transistors, each of them have different IP3?s.

For this program, my concern is for low power applications 1-5watts (small - medium power transistors). These days data sheets contain very little noise or distortion data. What parameters within the transistor affect a small or medium power transistor?

A good choice is always a CATV transistor or any other transistor for linear applications. FET's are more difficult to match wide band but for the same DC input seem to be better. BIP transistors used to be available for antenna distribution systems. Phillips, Infineon are always good suppliers.