If I connect, say 3 or 4 MOSFETs in parallel, to increase current capability, spread heat, and reduce cost..
They are connected in parallel, as in gate-gate, source-source, drain-drain.
It should have 3 times the gate capacitance, but that shouldn't affect speed,
3x the max current,
1/3 the on state resistance.

Right?
What happens to the transconductance?
If it's used as a switch is there a potential problem if they don't turn on all at the same moment, even if only nS apart?

Need help, thanks.

 

3 times the gate capacitance, also means that the driver needs to be three times as powerful, othervise it would affect speed.

If one is slightly slower/faster than the other wouldn't matter as long as they don't operate at very high frequency. If the switching loss is high, the slow/fast transistors will take more heat dissipation than the other.