Okay, so here's a basic question I can't find the answer to by googling... when they talk about N channel FET, what is the equivalent transistor of this in the other notation? Is it NPN or PNP? I.e. the "N" in "N" channel, what N is is this referring to in the other notation: NPN or PNP ?
NPN and PNP devices are bipolar junction transistors. N and P channel devices are field effect transistors.
Attempting to equate them will be as fruitful as trying to equate an egremont russett apple with a navel orange.
Both transistor types (BJT vs. FET) work completely different.
That means: The only properties you can compare are perhaps the polarities of the both relevant voltages which are required to cause a current and/or a current change with the same direction.
This attempt leads to the following:
* N-MOS (enhancement): VDS>0 and VGS>0 to be compared with BJT (npn): VBE>0 and VCE>0.
* P-MOS (enhancement): VDS<0 and VGS<0 to be compared with BJT (pnp): VBE<0 and VCE<0.
Hence, the above approach only allows to compare the BJT with an NMOS-FET (enhancement).
i find this video very informative
i didnt know mosfets bottleneck like that (do they still?)
i find this video very informative
i didnt know mosfets bottleneck like that (do they still?)
NPN and PNP devices are bipolar junction transistors. N and P channel devices are field effect transistors.
Attempting to equate them will be as fruitful as trying to equate an egremont russett apple with a navel orange.Yes I know, it was more about the logic of the gate voltages that control how it switches on and off that I was comparing them by, as described by LvW below:
To say that a BJT is not a current controlled device is arguing semantics. It's not the current that directly controls the transistor per se, but you need to maintain a current between the base and the emitter in order to control Vbe.
MOSFET types would always confuse me, as when I was a kid learning electronics someone told me NPN transistors Never Point iN, but N-Channel MOSFETS *do* point in and I couldn't get the phrase out of my head!
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a certain DC voltage Vbe is necessary to "open" the transistor and to allow a the desired quiescent current Ic (nobody will deny this fact), and
Okay, so here's a basic question I can't find the answer to by googling... when they talk about N channel FET, what is the equivalent transistor of this in the other notation? Is it NPN or PNP? I.e. the "N" in "N" channel, what N is is this referring to in the other notation: NPN or PNP ?
OMG! Seriously! I have never heard this voltage controlled BJT statement ever in 42 years.
I haven't ever met a single designer of transistors nor thesis suggesting your statement.
If you hadn't mentioned "students" I would not have replied. But if there is a chance you are a teacher/instructor/prof summarizing a BJT is sometimes a voltage controlled device to explain a schematic. I beg you to stop and research the physics more to come up with a better explanation.
Quotea certain DC voltage Vbe is necessary to "open" the transistor and to allow a the desired quiescent current Ic (nobody will deny this fact), and...........
The problem is that you are applying "circuit" theory in a manner that separates current from potential. One simply cannot happen without the other.
As my reply - just two sentences: I cannot see where I have "separated" current from potential (voltage). The basic question is: Is it the voltage that causes a current or is it the current that causes a voltage?
i find this video very informative
i didnt know mosfets bottleneck like that (do they still?)
If the base is driven by a high impedance (current source, collector of another transistor, etc), then Vbe will set itself depending on the current that is injected in the base, and you could say that the current causes a Vbe voltage. In this case, Vbe doesn't really matter.
BTW yes I understand the physics. And yes I do get your point. You are completely missing mine.
Yes because every single device made by man has inductive, capacitive and resistive properties every device can be said to be voltage controlled and current controlled. That is not the point being discussed.
The convention of calling a transistor a current controlled device....is a convention.