Explain in Depth of Transistor Amplifier

👉 What is a Transistor Amplifier?

A transistor amplifier is a circuit that increases the strength (amplitude) of a weak signal using a transistor.

👉 It converts a small input signal into a large output signal.

Example: Microphone signal → Speaker sound

🔹 Basic Principle of Amplification

A transistor works as an amplifier when it is operated in the active region.

👉 Small change in base current
➡ produces large change in collector current
➡ results in amplified output voltage

So:

👉 Small input → Large output

🔹 Common Emitter (CE) Amplifier

Most widely used amplifier.

Features:

• High voltage gain
• Moderate current gain
• 180° phase shift between input & output

Working:

1. Input signal is applied to base-emitter
2. Output is taken from collector-emitter
3. Coupling capacitors block DC and pass AC signal

🔹 Types of Transistor Amplifiers

1. Common Emitter (CE)

• High gain
• Most popular

2. Common Base (CB)

• High voltage gain
• Low input resistance

3. Common Collector (CC) (Emitter Follower)

• High current gain
• Used for impedance matching

🔹 Gain of Amplifier

Voltage Gain:

$$A_v = \frac{\text{Output Voltage}}{\text{Input Voltage}}$$Av​=Input VoltageOutput Voltage​

Higher gain = stronger amplification.

🔹 Applications

• Audio amplifiers
• Radio and TV circuits
• Communication systems
• Signal processing

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