27.2.1. Expression of Voltage Gain

Try these first

1. 1.

   Define voltage gain in the context of an amplifier.

   Hint

   Think about how voltage is amplified in a circuit.

2. 2.

   What does the negative sign in the voltage gain formula indicate?

   Hint

   Recall the phase relationship between input and output.

3. 3.

   What is the formula for the voltage gain of a common emitter amplifier?

   • A = -g_m * R_C / (1 + g_m * R_E)
   • A = g_m * R_C / (1 - g_m * R_E)
   • A = g_m * R_E / R_C

   Hint

   Look for the relationship between transconductance and the resistors involved.

4. 4.

   True or False: A larger emitter resistor will always increase voltage gain.

   • True
   • False

   Hint

   Consider the effects of component values on gain.

5. 5.

   Determine the effects on voltage gain if you increase $R_E$ from 1kΩ to 10kΩ, while keeping $g_m$ and $R_C$ constant. Explain your reasoning.

   Hint

   Consider how changing resistances affects the gain formula.

6. 6.

   If an amplifier circuit has a fixed input signal and you modify the output load resistance, what will be the impact on the voltage gain? Discuss the underlying principles.

   Hint

   Think about the output characteristics and load effect in circuits.