I always put a decoupling capacitor at the VCC pin of every component on my pcbs and this question derives from my habit to put decoupling capacitors on every power pin of the components I place.
I wonder about using decoupling cap on the Drain pin on N-Channel Mosfet, when using them in saturation mode (fully ON/ fully OFF).
Lets say I have this circuit, to make the question more specific (as this is the circuit I am working now):
Here is my thought: The Drain pin will originally have the voltage of lets say 12V, but when I give a signal to the Gate of the mosfet (driving it to saturation) the Drain pin will have a near-Zero volts. So the decoupling capacitor seems pointless to me at that point, as I do not need to "de-couple" the Drain of Mosfet from anything. I need it to do the opposite actually, short itself to GND and draw current. Using a capacitor (C1) there will only make the "short" delay some nanoseconds more, since it will have to discharge as well.
My thought is, I do not need to use a capacitor at the Drain pin of a mosfet, when Driving it in saturation mode?. Is there a reason I should use a Capacitor there when I simply need to turn on and off a resistive load?