Simple question about KVL Equation in a BJT Circuit

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    Bjt Circuit Kvl
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Discussion Overview

The discussion revolves around deriving the Kirchhoff's Voltage Law (KVL) equation for a Bipolar Junction Transistor (BJT) circuit to find the base current (Ib). It involves exploring the relationships between various currents in the circuit and the voltage drops across components.

Discussion Character

  • Homework-related
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant presents an initial KVL equation: Vcc - IcRc - IbRb - Vbe = 0, but expresses uncertainty about its correctness.
  • Another participant questions the validity of the voltage drop across Rc being represented as IcRc, suggesting it may not be entirely accurate.
  • A later reply proposes that the relationship between base current (Ib) and collector current (Ic) involves the emitter current (Ie), indicating that IeRc might be a more appropriate representation for the drop across Rc.
  • One participant agrees with the need to adjust the original equation by adding an IbRc term and advises against using Ie in the equation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct form of the KVL equation, and there are competing views regarding the correct representation of the voltage drops and the relationships between the currents.

Contextual Notes

There are unresolved assumptions regarding the definitions of the currents and the specific circuit configuration, which may affect the validity of the proposed equations.

ryNze
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Homework Statement



I am trying to find the KVL equation for this BJT in order to find Ib.
http://www.ece.auckland.ac.nz/oasis/a/att/qtatt/2028/2/261/IM010


Homework Equations





The Attempt at a Solution



My current equation looks like this.
Vcc - IcRc - IbRb - Vbe = 0

I am not entirely sure if this is correct.
 
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1. Is the drop across Rc really just IcRc? (Hint: you're close, but no cigars).
2. More importantly, what is the relationship between Ib and Ic for a BJT?
 
rude man said:
1. Is the drop across Rc really just IcRc? (Hint: you're close, but no cigars).
2. More importantly, what is the relationship between Ib and Ic for a BJT?

I just thought about it.
The base current and collector current equals to the emitter current.

So, the drop across the Rc is actually IeRc?
 
Yes. Add the IbRc term to your original equation, don't use Ie.

Now for part 2?
 

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