Questions tagged [ebers-moll]
The ebers-moll tag has no usage guidance.
13
questions
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43 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
87 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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93 views
T Model of a transistor
I want to redraw this circuit based om the T model.
Is this T model representation correct?
Where Zth is the parallel between R1 and R2 in series with C1, re = (Vt/Ie)
Vt being the early voltage, Z2 ...
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98 views
Transistor current source \beta varies (AoE Ex. 2.23)
I am having trouble solving the following exercise:
Exercise:
If \$ \beta \$ varies from 50 to 100 for collector voltages within the output compliance range, how much will the output current vary? (...
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1answer
81 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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109 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 ...
5
votes
1answer
196 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
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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
170 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 \$...
3
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1answer
260 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
162 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 ...
1
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1answer
169 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
860 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 ...
