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.
* Can you explain, for example, the function of the simple current mirror without using the voltage-control principle?
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.
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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.
Sent from my iPad using TapatalkI agree, it is a ridiculous statement, one from someone who doesn't understand the physics of how the devices work. Obviously, one can observe a varying base-emitter voltage with varying collector current. That does NOT imply that the collector current is controlled by base-emitter voltage. Correlation does not imply causation.
Yes it is funny how a simplified statement created to remember the primary datasheet characteristic curve general shape has turned into a subject of such debate.
Besides last time I checked there hasn't even been a consensus across the physics word on what the definition of current is. . Personally my definition is : it's the A in ohms law.
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Yes it is funny how a simplified statement created to remember the primary datasheet characteristic curve general shape has turned into a subject of such debate.
Besides last time I checked there hasn't even been a consensus across the physics word on what the definition of current is. . Personally my definition is : it's the A in ohms law.
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Actually there is, what current is well defined.
http://www.si-units-explained.info/ElectricCurrent/
I agree, it is a ridiculous statement, one from someone who doesn't understand the physics of how the devices work.
Lastly I believe the issue with explaining the offered ccts with the offered convention is you are mixing the different order conventions. The convention of BJT are current controlled devices is a first order convention that happens to be useful in second order just like in first order a resistor is considered to be purely resistive and at higher orders their inductance and capacitance is taken into account.
I spoke about physical effects
the technical fact of BJT`s voltage-control is emphasized by many serious and credible engineers/scientists
Appeal to authority probably isn't the best argument in any discussion. There are just as many morons among "serious and credible" experts as they are among lay persons, regardless of how many books such experts may have published.
It is precisely the physical effects that dictate such devices to be current controlled rather than voltage controlled. a NPN works through electron combination at the b-c junction. So if you control the electrons flowing into the base, you have controlled the collector current. So this whole thing is current (=charge / time) driven or controlled.
Appeal to authority probably isn't the best argument in any discussion. There are just as many morons among "serious and credible" experts as they are among lay persons, regardless of how many books such experts may have published.
Did you realize that this was only one of three arguments?
It would be interesting to learn how YOU would explain why a resistor RE increases the input resistance of a common emitter stage and/or how the tanh function of a diff. amplifier is derived?
I wouldn't mind giving it a shot, if you could tell me 1) how those questions and associated answers support your assertion or disproves the other side's arguments; and 2) what is "resistor RE" and "tanh function".
Explain it in as plain language as you can, or you don't understand it.
It's the carriers flowing across the BC junction which cause the transistor to conduct, but you don't get to push them across that junction yourself. I'd like to see how you plan to do that. (Possibly something involving voltage?) Applying a voltage between base and emitter draws carriers up from the emitter, and most pass to the collector because of device geometry. This is a result of the voltage across the BE junction. Applying current to the base does not force a proportional current to flow to the collector, it's the voltage that develops as a result of the current that pulls the carriers from the emitter.
Lastly I believe the issue with explaining the offered ccts with the offered convention is you are mixing the different order conventions. The convention of BJT are current controlled devices is a first order convention that happens to be useful in second order just like in first order a resistor is considered to be purely resistive and at higher orders their inductance and capacitance is taken into account.Hi warsim - I am afraid, it makes not too much sense to continue this discussion.
Perhaps we have a communication problem due to different languages.
(Quote: „I am not going to discuss physics here“). My question: Why not ? From the beginning, I spoke about physical effects - and you are stressing „conventions" of first and higher order only. I do not know any document, article or textbook which classifies the control mechanism of a BJT as a pure "convention" only.
I must admit that I am a bit disappointed not to see any answers to my pure technical and circuit-oriented questions in my posts#17 and #22. I think, we all are engineers and should be able and willing to answer technical questions?
OK - let`s stop the „discussion“ (unfortunately in most parts non-technical) and let me summarize:
1.) Up to now, I have seen not a single publication/textbook which contains some arguments against the voltage-control property of BJT`s (simply stating it would be current-controlled is no counter argument).
2.) However, there are many circuit-based effects and examples (and I have listed some of them in post #17 and #22) which can be explained using voltage-control only (and NOT on the basis of current-control). Unfortunately, no comments from your side.
3.) More than that, the technical fact of BJT`s voltage-control is emphasized by many serious and credible engineers/scientists (see some examples in my former post#33).
Now - every reader of this thread may create his own view.
You are an argumentative arse.
...............
You are creating a disagreement where there isn't one.
why the input impedance of an emitter follower is high.
Ic = beta Ib
If you want to help answer the OPs question answer their question appropriately.
If you want to help answer the OPs question answer their question appropriately.Perhaps you have overlooked that I have answered the OP`s question in my post#6.
But I agree with you - it would have been better to open a new thread for dicussing the BJT control mechanism.
Why didn`t you come up with this earlier?
If you want to debate the physical model then start a thread for that purpose. Hijacking this thread for this debate is considered rude by accepted forum behaviour.