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5.2 Give TWO reasons for biasing a transistor - NSC Electrical Technology Electronics - Question 5 - 2018 - Paper 1
Question 5
5.2 Give TWO reasons for biasing a transistor. 1. To set the operating conditions (points) of the transistor. 2. To stabilise the operating point of the transistor.
Worked Solution & Example Answer:5.2 Give TWO reasons for biasing a transistor - NSC Electrical Technology Electronics - Question 5 - 2018 - Paper 1
Step 1
Give TWO reasons for biasing a transistor.
Answer
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Biasing ensures that the transistor operates in the desired region of its characteristic curve, allowing it to amplify signals effectively.
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It helps to stabilize the operating point against variations in temperature and transistor parameters, ensuring consistent performance.
Step 2
Explain the term Q-point on a DC load line.
Answer
The Q-point, or quiescent point, refers to the specific voltage and current levels at which the transistor operates when no input signal is applied. It is positioned on the DC load line and represents the optimal point where the transistor can amplify an AC signal over its full range without distortion.
Step 3
Indicate the Q-point of a class A, class B and class C amplifier on ANSWER SHEET 5.2.3.
Answer
The Q-point for class A biasing is typically set at the midpoint of the load line, allowing for full signal amplification. Class B operation has the Q-point at the cutoff, while class C is placed just below cutoff to provide a high output for high-frequency signals.