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  1. LvW

    How a BJT Transistor works (base current version)

    Ratch - in this respect, I am not with you. For my opinion, we do not necessarily need the device physics. I have mentioned already some tests (supported by corresponding formulas) which could reveal the "secrets" of Ic control. Here again is a short survey: * We can measure the form of the...
  2. LvW

    How a BJT Transistor works (base current version)

    Hi Claude, some comments to your reply. "If a CVS is attached to the base w/ emitter grounded, then of course the CVS value, which equals external Vbe, will determine or "control the current"." Ohh - some new words from your side. Sounds good. "But such a connection is thermally stable MAYBE...
  3. LvW

    How a BJT Transistor works (base current version)

    Gentlemen - I must admit that I am not a specialist in charged carrier physics. Hence, I cannot comment on most of your last statements. I was educated as an engineer - therefore, I think as an engineer and I have worked as an engineer for many years. For this reason, I primarily rely on...
  4. LvW

    How a BJT Transistor works (base current version)

    Hi Ratch, it was just two days ago that something came into my mind: There is a handwritten paper from Claude (a pdf copy must be somewhere on my hard disc) which contains a comprehensive calculation of a classical BJT amplifier with RE-stabilization. Given are all resistor values, the ratio...
  5. LvW

    How a BJT Transistor works (base current version)

    Claude - here is my conclusion: You are the only person who does not use a Vbe voltage of app. 0.65 volts for "opening" the BJT to have an emitter current of some milliamps. I wonder how you are designing BJT gain stages. I suggest to stop the exchange of opinions (assertions) now. LvW
  6. LvW

    How a BJT Transistor works (base current version)

    Claude - thank you for providing the excerpt from the Ebers-Moll paper. Without reading (and understanding) the whole text - my first impression is the following: 1.) This part discusses common-base configuration only. 2.) The current Ie contains an exponential term with the emitter potential...
  7. LvW

    How a BJT Transistor works (base current version)

    Claude - as I have mentioned already: We should agree not to agree. I do not intend to go into details of your long contribution (post#100). Either you are explaining physical details not under discussion or you are misinterpreting some effects - exclusively under your point of view: Ie...
  8. LvW

    How a BJT Transistor works (base current version)

    More than that - all measurements, experiments, observations proof this (Early effect, -2mV/K, Re-feedback, diff. amplifiers with tanh-transfer, class-B form of cross-over distortions, current mirror, translinear loops,...). In particular, the design of BJT stages is based on voltage control...
  9. LvW

    How a BJT Transistor works (base current version)

    Yes - me too. By the way, one can show that - based on the law of energy conservation - it is impossible that a small current can DIRECTLY control a larger current. In general, I do not rely too much on simple analogies - however, just for illustration purposes: It is easy to justify this law...
  10. LvW

    How a BJT Transistor works (base current version)

    "The reason I mention chickens and eggs is because some questions are futile. In general does current control voltage, or the other way around? One can cite examples either way, but science proves that I & V under dynamic conditions mutually coexist, neither in general is the controller or cause...
  11. LvW

    Differential amplifier single ended output calculations

    What do you mean with this part of the sentence?
  12. LvW

    Differential amplifier single ended output calculations

    I am not quite sure what do you intend to do. You did a simulation - and you want to find the simulation results by hand calculations? Is that true? In this case, I must tell you that this seems to be impossible because you have used during simulations a real BJT model with many non-idealities...
  13. LvW

    Differential amplifier single ended output calculations

    No - that`s not an equation for the Early voltage. Note this is the equation for the collector current dependence on the B-E voltage. Hence - the input-output transfer characteristic for the BJT. The Early voltage is a measure for the slope (g,ce=1/r,ce) of the output curves Ic=f(Vce) with...
  14. LvW

    Differential amplifier single ended output calculations

    Yes - I agree to Adam`s (Vbe drop) as well as KrisBlue`s comments (Early effect). Moreover, we can expect a corresponding (small) difference in base currents because Vbe is equal for both transistoirs.
  15. LvW

    How a BJT Transistor works (base current version)

    Claude - I am afraid, you are mixing two things. As far as I understand, we are discussing here the working principle of a BJT - and NOT how to design a temperature and tolerance stabilized gain stage. It is really not necessary to repeat all the problems connected with temperature effects. I...
  16. LvW

    How a BJT Transistor works (base current version)

    Quote Claude: "Yes, gate current precedes gate-source voltage." Claude, it took a long time until - I hope so - I was able to understand your way of thinking (and your definition of "control").. To make it clear to me: I think, you would NOT agree that a dc motor is controlled by a dc voltage...
  17. LvW

    How a BJT Transistor works (base current version)

    " How can V exist before I in a p-n junction?" Claude - to understand your way of thinking, let me ask the following question: Does this (I before V) apply also for the gate-source path of FET`s (charging the input capacitance) ?
  18. LvW

    How a BJT Transistor works (base current version)

    Yes - the slide I have cited long time ago does not contain a proof. But note: It is one single slide with (estimated) 10 words and 3 formulas - do you expect a derivation on a single slide,? Not a good counter example.! If you are interested in the university papers with extensive derivations -...
  19. LvW

    How a BJT Transistor works (base current version)

    Are you joking? Do we speak about complete circuits - stabilized against tolerances and temperature sensitivity - or about a physical working principle? Did you realize that in my simulation example (post 38) I have directly applied the voltage Vbe? PLease, would you be so kind and tell me...
  20. LvW

    How a BJT Transistor works (base current version)

    Adam, do you think that the general working principle of the BJT depends on the applied frequency? I rather think, we have the same situation as for ALL electronic parts: They follow a certain working principle and they do what they are supposed to do (up to nearly 100%) - as long as no...
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