Common Emitter Transistor Amplifier

A common emitter transistor amplifier is a configuration that is widely used in audio amplification circuits. It provides voltage amplification and allows for a relatively high input impedance and low output impedance. Let's analyze the given information to determine the voltage and power gain of the amplifier.

Given Values:
- Audio signal voltage across the collector (Vc) = 3V
- Resistance of collector (Rc) = 3 kilo ohm
- Current gain (β) = 100
- Base resistance (Rb) = 2 kilo ohm

Voltage Gain (Av):
The voltage gain of an amplifier is given by the ratio of the output voltage to the input voltage. In this case, the output voltage is the voltage across the collector (Vc), and the input voltage is the voltage across the base (Vb).

We can calculate the voltage gain using the formula:

Av = -β * (Rc / Rb)

Substituting the given values:

Av = -100 * (3 kilo ohm / 2 kilo ohm)
Av = -100 * 1.5
Av = -150

The negative sign indicates an inverted output compared to the input.

Power Gain (Ap):
The power gain of an amplifier is the ratio of the output power to the input power. Power is calculated using the formula:

P = V^2 / R

Where P is power, V is voltage, and R is resistance.

The output power can be calculated using the formula:

Po = Vc^2 / Rc

Substituting the given values:

Po = (3V)^2 / (3 kilo ohm)
Po = 9V^2 / 3 kilo ohm
Po = 9 / 3
Po = 3W

The input power can be calculated using the formula:

Pi = Vb^2 / Rb

Since the input voltage (Vb) is not given, we cannot directly calculate the input power. Therefore, it is not possible to determine the power gain (Ap) without the input voltage.

Summary:
- The voltage gain of the amplifier is -150, indicating an inverted output compared to the input.
- The power gain (Ap) cannot be determined without the input voltage.
- The given values allow us to calculate the output power (Po) of the amplifier, which is 3W.