Questions tagged [ebers-moll]

For questions about the Ebers-Moll model for bipolar junction transistors (BJTs). Always use in conjunction with the "bjt" tag.

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On the huge error between LTSPICE and Ebers-Moll when vCE=0 for a BJT

Let us assume that we have a npn BJT with parameters similar to 2N2222 in LTSPICE at T=27 C The thermal voltage at T=27C is VT=25.865 mV Let us assume that VCE=0 and VBE=0.85 V From 2N2222 in LTSPICE ...
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The small-signal impedance looking into the emitter when base voltage is not fixed

In section 2.3.2 of the 3rd edition of The Art of Electronics, the small-signal impedance looking into the emitter, \$r_\text{e}\$, for the base held at a fixed voltage is defined as "the ...
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How do you use an LED's log V/I curve to force an exponential current change in the LED for a linear voltage change?

The info needed to make log and exponential converters with silicon is widely available. The saturation current, intrinsic resistances, and the Ebers-Moll equation are sufficient. A few other numbers ...
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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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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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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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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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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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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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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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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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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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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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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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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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Can you find an analytic expression for the (beta)hfe of a BJT?

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