# Solve BJT Transistor Q Point Using Thevenin Theorem

• Engineering
• Dominik
In summary, a BJT transistor is a type of transistor used in electronic circuits as an amplifier or switch. The Q point, or operating point, of a BJT transistor is the point where it operates on the DC load line and determines its output voltage and current. Thevenin's theorem is a method for simplifying complex circuits into a single voltage source and impedance. To solve for the Q point, the Thevenin equivalent circuit is determined and used with the standard load line analysis method. The advantages of using Thevenin's theorem include simplifying the circuit, eliminating tedious calculations, and providing a more accurate and efficient method for both AC and DC circuits.
Dominik
Homework Statement
Find Q point of a BJT transistor
Relevant Equations
Q(Ib,Ic,Ube,Uce), Ube=0.7V
Hello,

I need help with this bjt transistor and finding the Q point. The problem I have is that I don't know how to do the thevenin theorem on this one. If someone could help me and show me how its done that would be great. Thank you!
The transistor looks like this on the picture:

This is my attempt at doing it but don't know if its correct:

Thanks for the very high quality image of your work @Dominik (not) -- Could you please try again? Thanks.

Last edited:

## 1. What is a BJT transistor?

A BJT (Bipolar Junction Transistor) is a type of semiconductor device that is commonly used in electronic circuits for amplification or switching of electrical signals. It consists of three layers of doped semiconductor materials, namely the emitter, base, and collector.

## 2. What is the Q point of a BJT transistor?

The Q point, also known as the operating point, is the DC bias point at which the BJT operates in an active region. It represents the combination of collector current (IC) and collector-emitter voltage (VCE) at which the transistor is biased for proper operation.

## 3. What is Thevenin's theorem?

Thevenin's theorem states that any linear electrical network containing voltage and current sources can be replaced by an equivalent circuit consisting of a single voltage source and a single resistance connected in series. This equivalent circuit is known as the Thevenin equivalent circuit.

## 4. How can Thevenin's theorem be used to solve for the Q point of a BJT transistor?

Thevenin's theorem can be used to simplify the analysis of a BJT transistor circuit by reducing the circuit to a single voltage source and a single resistance. This equivalent circuit can then be used to calculate the Q point of the transistor by applying the principles of DC circuit analysis.

## 5. What are the steps for solving the Q point of a BJT transistor using Thevenin's theorem?

The following are the steps for solving the Q point of a BJT transistor using Thevenin's theorem:

1. Identify the BJT transistor circuit and determine the load resistance.
2. Calculate the Thevenin voltage (VTH) and resistance (RTH) of the circuit by removing the load resistance and finding the open-circuit voltage and short-circuit current, respectively.
3. Replace the BJT transistor circuit with the Thevenin equivalent circuit (VTH and RTH in series).
4. Apply DC circuit analysis to the Thevenin equivalent circuit to find the Q point.

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