Questions tagged [ebers-moll]

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Do Ebers-Moll model cover all working modes of BJTs?

I mean the normal working modes (cutoff, forward/reverse active, saturation). Or an other form of the question: Do Ebers-Moll cover the whole working domain of BJT (in potential and current values)?
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17 views

What is value of Reverse Saturation Current (Is) for BC547B NPN transistor

I am trying to evaluate Ebers Moll equation for estimating collector current for a given V_BE at DC conditions. The datasheet of BC547B (which I am using) does not mention the Is (i.e. Reverse ...
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14 views

Derive the expressions for the i-v characteristics of these configurations of NPN Transistors. Part (a)

I just need part (a) to be solved because then b would be trivial. I am using the Ebers-Moll model equations but somehow my final solution doesn't have alpha_F and alpha_R and i know that shouldn't ...
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2answers
107 views

How to use Ebers-Moll equation to calculate collector current?

The Ebers-Moll equation is given by:$$I_C = I_S(T) * (e^{V_{BE}/V_T})$$ where \$V_T\$ = \$kT/q\$ = 25.3mV at room temperature. In TAOE (2.3.1), it mentioned \$I_S(T)\$ is the saturation current of ...
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70 views

How to calculate Current Emitter (Ie) using Eber-Molls model on an NPN transistor

my computer science professor gave us a problem to code in python involving Ebers-Moll model for circuits where he asks us to find the current emitter (Ie). In the program we ask the user to give us ...
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1answer
118 views

Question on Ebers-Moll model

I have what should be a simple misunderstanding of a piece of text from "RF Circuit Design" by Lugwig. I am not in a class, just self-teaching. This book has been quite helpful, and I have not found ...
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1answer
146 views

What part of Ebers-Moll equation shows the decrease of the collector current in saturation region

By looking at the Ebers-Moll equation for a BJT transistor: Is this formula explicitly showing why Ic starting to decrease towards zero in saturation region. Which part of the equation shows that?
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146 views

Reverse biased diode formula in Ebers-Moll model

As far as I understand in an PNP transistor the base voltage Vb is higher potential than the collector voltage. So since Vb>Vc the base collector junction is then reverse biased: But in Ebers-Moll ...
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1answer
216 views

Operation of BJT with low values of Vbe (“cutoff” region)

Many sources claim that when the base-emitter voltage becomes smaller than approximately 0.6V-0.7V, the bipolar junction transistor goes in the cutoff region and there is zero base and collector ...
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1answer
1k views

Saturation current in Ebers-Moll equations for BJT: what is it and how to measure it?

In Ebers-Moll Equations for common emitter BJT the inverse saturation current \$I_s\$ appears as a parameter. What is the saturation current \$I_s\$ exactly and how should I measure in a common ...
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2answers
194 views

Ebers–Moll model aF? Where does it come from?

I am just getting back into electronics after a long while. For the life of me I can't figure where the \$\alpha_F\$ variable in the Ebers–Moll model comes from when you are calculating \$I_C\$ or \$...
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1answer
326 views

An NPN BJT - from Spice to Ebers-Moll

Wikipedia reports a simple model for a BJT in active mode (an approximation to the Ebers-Moll model): \$I_E=-I_{ES}(e^{V_{BE}/V_T}-1)\$ (in the NPN case). Here, \$I_{ES}\$ is the Base-Emitter ...
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1answer
175 views

Which equation of the Ebers-Moll-Model is correct?

I'm confused. In different sources sometimes I find the equation \$ I_C = I_S\cdot\left(e^{\frac{U_{BE}}{U_T}}-1\right) \$ or like wikipedia \$ I_C = I_S\cdot e^{\frac{U_{BE}}{U_T}} \$ Can ...
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1answer
202 views

Collector currents of different BJT Models and Ebers-Moll

Per Horowitz&Hill book, the Ebers-Moll equation for the collector current in a BJT is: Ic = Is (e ^ (Vbe/Vt) - 1) where Ic is the collector current and Is is the saturation current. Now, I am ...
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5answers
981 views

Can you find an analytic expression for the (beta)hfe of a BJT?

I understand there are two models \$Ic=\beta Ib\$ and \$Ic=I_s exp (\frac{V_{BE}}{Vt})\$ for a bipolar junction transistor. However (correct me if I am wrong), I have not seen any textbook ...