I have been looking at various types of transistors that can switch at higher speeds than my clunky but powerful IGBT, and I came across these things called "rf transistors" or "rf mosfets" which can switch at speeds anywhere from a few mhz to a few ghz. Here is an example datasheet. I was wondering what makes these things so fast. I tried some googling, but all I could find was products–no details on what exactly makes these devices different.
Also, is there anything I should watch out for when driving one of these devices? I have gotten fairly comfortable driving large IGBTs and other power devices, but I definitely experienced a learning curve. For example, it took some time and a fair amount of burned out transistors to realize I had to isolate the voltage that drives the gate from source-drain voltage. I also learned that although a resistor connected to the gate is not necessary, a small one helps get you a cleaner signal (I suspect it prevents ringing between the secondary of a gate drive transformer and the effective capacitance between the gate and source). Finally, I found that for fast switching, it helps to actively pull the gate voltage below zero rather than just let it drain across a diode. So given that these are some things I learned to watch out for when driving power transistors, are there any new caveats I should watch out for when working with rf transistors?