wbeaty said:
Yes, that's just the Ebers-Moll model of BJT operation: taken from basic diode physics. If you object to Ebers-Moll, or object to the conventional explanation of semiconductor rectifiers, you need to list their failings first. It's impossible to have any sort of discussion as long as you're attacking common textbook material.
For anyone interested in understanding BJTs, I strongly suggest that you don't listen to transistor OEMs, but instead take a look at undergrad engineering texts such as Horowitz and Hill's AOE book. They start out with a simplified "little man inside the transistor" approach where Ic is controlled by Ib via the "Transistor Man." Then they go on to "Improved transistor model: transconductance amplifier;" introducing the Ebers-Moll equation to show how Ic varies with Vbe, and give a list of "Rules of thumb for transistor design" based upon it.
My article "How transistors work" is just a visual/verbal explanation of the Ebers-Moll BJT model for beginners, with math removed (it's Babylonian rather than Euclidian: re-stating basic semiconductor concepts from undergrad textbooks so your children and grandparents can understand.)
When experts state that "BJTs are voltage controlled," they're really just saying that if we stop treating transistors as black boxes, and instead look inside that box, we find that they are well described by the Ebers-Moll equation.
The "transconductance" amp, is only valid for small signal action. For large signals, "gm" is not well defined, as it varies with Ic, the dc value of collector current.
Experts regard bjt's as "charge controlled", and this is consistent with OEMs, and semiconductor physics. Regarding Ebers-Moll, the original 1954 paper, too big to post here, depicts the bjt as
2, current controlled current sources. One in the conventional mode, Ic = alpha*Ie, and the other upside down for reverse mode operation, useful in the saturated state. I'll send it to you if you wish. It gives an illustration showing the current controlled current sources.
All reputable texts and references depict the bjt as current controlled when viewed as a black box, then charge controlled at the micro scale. Ebers-Moll, which you cite, lists the bjt as current controlled where Ic is alpha*Ie. No OEM says otherwise.
The OEMs are not reliable? Get serious. They make the raw silicon crystal starting with a seed in the oven. They inject the dopants to form junctions using pretty sophisticated equipment, i.e. diffusion, ion implantation. Nobody knows the bjt like they do. Even the great Ebers & Moll got their info at some point from OEMs who produce bjt devices.
When you say that OEMs don't know it like you do, I can only reply "get serious". Do you produce semiconductors?
You simply cannot fathom any electrical device being current controlled. You insist that the whole electrical universe be defined in terms of voltage because you believe that fundamentally voltage is more important. It's merely a mental block. If the bjt was really voltage controlled, it would be universally known and stated by OEMs. Why would they call it CC when it's really VC? The FET (J- and MOS-) has been depicted as VC for as long as I can remember. Did they get the FET right? The fact that 1 is classified as CC, and the other as VC, indicates that there is a difference, and that they know from first hand knowledge producing both.
Enough for now. Cheers.
Claude
