Can someone please explain what is the purpose of Rg? I've found this explanation on another forum, but it still doesn't fully make sense to me:
"Basically, if you make RG too small then your FET might turn on very quickly which might cause noise in your circuit. If you make RG too large, then the MOSFET takes a long time to turn on -- this will increase the conduction losses in the MOSFET. This is because we really want to use the MOSFET as a switch -- ON (saturation) and OFF (cutoff). If we turn it on slowly, then the MOSFET spends much more time in the LINEAR (ohmic) region and it acts like a resistor and burns up power at each cycle."
Rg value too high making a slow switch is intuitive, but if we want to use the MOSFET as a switch and the intent is to turn it ON as fast as possible, why do we need a resistor at all? Can it be eliminated and what are the side effects? The author of the quote is suggesting it may cause noise, is it true?