Talk:Transistor

Voltage Controlled Bipolar Transistor

I have edited the text where the following statement is:

“By controlling the number of electrons that can leave the base, the number of electrons entering the collector can be controlled.[24]”

It is fundamentally not correct, and perpetuates misunderstandings as to how a bipolar transistor actually works.

Before my edits are considered to be reverted, please refer to the original Gummel–Poon_model paper cited at

http://en.wikipedia.org/wiki/Gummel%E2%80%93Poon_model

A direct quote from this Gummel-Pool paper is (P.828):

“…The new charge control relation arises from the treatment of the transport equation for the carriers that pass between emitter and collector. Use is made of the fact that recombination has only a very small effect on the junction-voltage dependence of the current passing from emitter to collector (later called the dominant current component). Hence for this dependence, but of course not for the base current, recombination is neglected. A direct closed-form solution of the transport equation from inside the emitter to inside the collector is possible…”

It is noted, recombination *is* the base current. Since this base current is neglected (initially) in the Gummel–Poon method of calculating the collector current from the base emitter voltage and collector voltage it is simply not reasonable to then claim that “the collector current is *controlled* by the base current”.

The “charge control” model, by design, as shown above, calculates the base charge resulting from the applied *voltages* at the base and collector. It is noted that the base charge is not the charge flowing out of the base, but the charge in the base region, which has no direct relation to the charge flowing out of the base.

So, fundamentally the bipolar transistor is a voltage controlled device. Any base current that flows is simply a nuisance, and not any way key to transistor operation. This is clearly the opinion of some of the most noted experts (Gummel-Pool) on transistor theory.

If any editor has a more academic *reliable* source that contradicts the Gummel-Pool voltage controlled view above, and can present the basics of an actual theory as to why the bipolar transistor would be base current controlled, present it here, or please leave my latest edits alone. Kevin aylward (talk) 13:02, 27 December 2012 (UTC)

' BJT is a current controlled voltage device but JFET is a voltage controlled current device. Explain it.'

One could argue that both devices are non-linear "voltage-controlled resistors", but the usefulness of a model is based on the ease and accuracy of creating or comparing a model with reality.

After reading the comparison http://www.designers-guide.org/VBIC/documents/ted00.pdf of the old (Spice-Gummel-Poon) SGP model with new VBIC ( Vertical Bipolar Inter-Company) model developed by a group from the Semiconductor Industry, I am convinced it is the better way to forward in use of SPICE models. The precise modelling requires sequential non-linear regression and then a tolerance of parameters to std.tolerances, which is not discussed and is non-trivial. However the results are clearly, far more accurately as a result of the regression feedback. ( Praise not to Allah, but the Semi guys who developed the model.)

For example the representation of Beta or current gain, where the mountain shaped curves "almost" have a plateau in only 3 decades out 10 for Ic ( 6,7&8 ). The last two decades are a steep cliff where saturation begins and Beta drops to 10 (on most devices)

So I hope they do replace the GP model with the VBIC model in SPICE for the benefit of future application designers.

But really, both transistors are just non-linear voltage controlled resistors. There's no "active" power source inside. But the sensitivity of this behaviour makes them "active" either have good small signal gain or large signal switch properties or impedance buffers (CC mode) depend on the circuit. This "active" region, I suppose is due to the "negative" resistance behaviour, as it often observed with any plasma tube or Fear mongering god. By Dean A. (Tony) Stewart from Linkedin discussion on this topic - Phillip (talk) 20:56, 14 July 2013 (UTC)

Origin of the name "transistor"

The Bell labs webpage Has a copy of the ballot used to determine the name of the transistor with the description of term 'transistor' given as a portmanteau of the terms 'transconductance,' 'transfer,' and 'varistor.'

The current article claims a portmanteau of the term 'transfer resistor.' I'm new to this so I thought I would ask if anyone has an opinion. — Preceding unsigned comment added by 130.63.86.178 (talk) 16:43, 24 March 2013 (UTC)

The ballot actually says "transconductance or transfer". I have to say that varistor makes more sense to me than resistor, but I note that varistor is itself a portmanteau of variable+resistor and that transistor has entirely lost the var element so transfer+resistor in not entirely wrong. The difficulty here is going to be sourcing. There are literally thousands of RS out there verifying transfer resistor. I could find only three results on gbooks for transfer varistor, only two or which are in English. It would be some task to show that these sources are more authoritative than the thousands of others. I do not think that the appearance of transfer varistor on a ballot paper settles the matter. This is a primary source and furthermore gives no indication of the result of the ballot or whether this interpretation was adopted. A press release from Bell Labs at the time, or the appearance of the term in their jourhanl would be much more convincing. SpinningSpark 19:03, 24 March 2013 (UTC)

History_of_the_transistor#Origin_of_the_term has JRP's own words on how he named it. Dicklyon (talk) 19:28, 24 March 2013 (UTC)

Package power rating table

I have cleaned up this edit from user:Magnus0re who inserted a table of transistor package power capabilities. However, I have concerns that a good deal of OR went into the construction of this table despite its heavy referencing. The "range" column seems to have been arrived at by examining a number of transistor data sheets and taking the extrema and the "approx." column by taking the average. This would make it a bad case of WP:SYNTH. I don't think packages have a minimum power rating so the range column is meaningless. More useful would be a sourced list of package maximum power ratings which one is not going to find in any transistor data sheet. SpinningSpark 11:28, 13 September 2013 (UTC)

- You are correct in assuming that the range column have been arrived at by taking the extrema. the approx column is just that, approximate, Yes it is a created number by comparing different datasheets.

My opinion is that the approx range may have a bad name, but I think it is true to the WP:SYNTH(no OR), because many reliable sources(hundreds, if not thousands of datasheets) exists that say that their transistor packages are capable of wattages in that range. Also the table is in line with the Neutral point of view and Verifiability, because it represents the approx number that is a more proportionate number than the maximum, (the maximum serves to promote one device while the approx serves to inform about what might be expected of a range of devices)

The reason I included both is because this is much more useful for a person trying to select a package(rather than only maximum values, because then the engineer will be looking for the one device with max. documented power handling, which is not good.), because there is only a few rare and expensive devices that can take the maxima. (in this case only a few mosfets, not bjts.) On second thought maybe the Approx column should be renamed into something like "assumed median value +/- 300% accuracy, consult individual datasheet". But the purpose of the column was to put a number to what can be expected of devices in that package. Is there a better name or better way to implement such a number? Magnus0re (talk) 12:40, 15 September 2013 (UTC)