Introduction: In some books and other technical papers (also from universities) it is - surprisingly - still claimed that the bipolar transistor (BJT) would be a current-controlled element. This is simply stated - without any explanation or proof (which I think is impossible).

But of course, the other representation (voltage-controlled) can also be found in many knowledge sources - just as it is considered in the SPICE models.

For me and also for many students this is an unsatisfactory situation. Therefore, I consider the distinction (current vs. voltage-control) to be very important to avoid contradictions between theory and practice. Because many circuits and observable effects can only be explained with voltage control Ic=f(Vbe).

As one argument pro current control often the output characteristic Ic=f(Vce) is referred to, where the base current Ib is considered as a fixed parameter (Ib=const). And - as a matter of fact: Although the collector current Ic is determined by the voltage Vbe, the characteristic curves Ic=f(Vce) are practically always given only for different (fixed) base currents Ib.

My Question: Why ?

EDIT: In response to Elliot Alderson`s comment I enclose a short contribution from the great Barrie Gilbert.

posted over 3 years ago

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9mo ago by Lorenzo Donati‭

LvW‭

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