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BrianG · 11.02.2007, 09:30 PM

Wow! First of all, let me say you are tackling a complex project here!

When you say PNP/NPN, I assume you are familiar with bipolar transistors. Transistors are "current" driven, have a current gain (beta), and have a set collector to emitter voltage drop even at saturation. MOSFETs are voltage driven (they don't load down driving circuits) and their drain to source v drop is determined by the Rdson value and current flow. Think of them more like a faucet where the source is the water tank, the drain is the output, and the gate is the valve. Rough analogy, but sufficient. There are other differences, but you see what I mean - it's like comparing apples to oranges.

Aside from being N or P channel, are they enhancement or depletion types? I would think you would NEED enhancement types, but I dunno.

Sorry I can't help you any further on this as I've never really dealt too much with FETs at the design level.

The Quark 125 uses the same FET parts, just more of them. IIRC, they are the same on both sides.

	(#2)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	11.02.2007, 09:30 PM Wow! First of all, let me say you are tackling a complex project here! When you say PNP/NPN, I assume you are familiar with bipolar transistors. Transistors are "current" driven, have a current gain (beta), and have a set collector to emitter voltage drop even at saturation. MOSFETs are voltage driven (they don't load down driving circuits) and their drain to source v drop is determined by the Rdson value and current flow. Think of them more like a faucet where the source is the water tank, the drain is the output, and the gate is the valve. Rough analogy, but sufficient. There are other differences, but you see what I mean - it's like comparing apples to oranges. Aside from being N or P channel, are they enhancement or depletion types? I would think you would NEED enhancement types, but I dunno. Sorry I can't help you any further on this as I've never really dealt too much with FETs at the design level. The Quark 125 uses the same FET parts, just more of them. IIRC, they are the same on both sides.