Electronics / 2nd Year Preparatory cycles
Dr. Nabila NOUAR
2024-2025
Worksheet 3
Bipolar Junction Transistor
Exercise 1 :
We consider the opposite circuit with a BJT transistor.
Q1. Show that the transistor is operating in the linear zone
and determine its operating point.
𝑅𝐵 = 10𝑘Ω , 𝑅𝐶 = 50 Ω, 𝑉𝐶𝐶 = 10𝑉, 𝛽 = 100 , 𝑉𝐶𝐸𝑠𝑎𝑡 = 0.2 𝑉
Q2. Considering the same circuit but 𝑅𝐶 = 1000 Ω.
Show that the transistor is operating in the saturation region.
Determine the collector current 𝐼𝐶 and show that 𝐼𝐶 = 𝛽𝐼𝐵 is no longer
valid.
Exercise 2 :
Determine the values of the four resistors so that the operating point has :
𝑉𝐶 = 6𝑉 , 𝑉𝐸 = 2𝑉 and 𝐼𝐵 = 100 𝜇𝐴.
𝛽 = 150 , 𝑉𝐶𝐶 = 10𝑉
Exercise 3 :
-What is the name of this circuit ?
-What is the expression of VC and what is its value?
We suppose that both transistors are identical
𝛽 = 100 ,𝑅𝐵 = 8 𝑘Ω , 𝑅𝐶 = 27 Ω , 𝑉𝐶𝐶 = 15𝑉
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Electronics / 2nd Year Preparatory cycles
Dr. Nabila NOUAR
2024-2025
Exercise 4 :
We consider the common emitter amplifier circuit, where
the BJT is operating in its linear zone.
Present the equivalent scheme in AC (dynamic analysis)
Exercise 5 :
The opposite circuit refers to a common base amplifier.
Determine the voltage Gain, the current Gain and present
the equivalent scheme in AC.
We consider that 𝑅𝐶 and ℎ11 are of same order
