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NPN / N-channel

M

Matt Krass

Jan 1, 1970
0
I'm diving back in to discrete component circuit design again after a
few years, and I'm blanking out, is there any functional difference
between an n-channel transistor and an NPN, same for p-channel PNP
transistors?

Thanks.
 
P

Phil Allison

Jan 1, 1970
0
** Worried Groper alert !

I'm diving back in to discrete component circuit design again after a
few years, and I'm blanking out, is there any functional difference
between an n-channel transistor and an NPN, same for p-channel PNP
transistors?


** The word "channel" implies the device is a FET ( Field Effect
Transistor).

Lots of interesting differences between a FET and a BJT (ie Bi-polar
Junction Transistor)

Do a Google search......



........ Phil
 
D

DJ Delorie

Jan 1, 1970
0
Matt Krass said:
I'm diving back in to discrete component circuit design again after
a few years, and I'm blanking out, is there any functional
difference between an n-channel transistor and an NPN, same for
p-channel PNP transistors?

*If* the device is a MOSFET (and not a JFET), you can *almost* treat
them the same as BJTs, at least for switching.

Similarities:

drain = collector
source = emitter
gate = base

driving base relative to source enables current from drain to
source.

Differences:

BJTs are current controlled current devices.
MOSFETS are voltage controlled resistor devices.
The response curve is different.

So, where driving a BJT with a base current (Ibe) enables a much
larger collector current (Ice), driving a MOSFET with a gate voltage
(Vgs) reduces the drain-source resistance (Rds). Also, the gate has a
small capacitance, so you not only have to drive it ON, but you have
to drive it OFF too. The capacitance also affects the frequency
response, so model it if you're doing high frequency work.
 
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