25.2. Small Signal Equivalent Circuit

Try these first

1. 1.

   What happens to capacitors in small signal equivalent circuits?

   Hint

   Think about how they behave in AC analysis.

2. 2.

   What is the equation for collector current I_C in terms of base current I_B?

   Hint

   Remember the relationship between base and collector currents.

3. 3.

   What does the small signal equivalent circuit treat DC values as?

   • Zero
   • Infinity
   • Constant

   Hint

   Consider the overall purpose of small signal analysis.

4. 4.

   True or False: V_out can become positive if I_C is negative.

   • True
   • False

   Hint

   Think about how current flows in the circuit.

5. 5.

   Given a CE amplifier with R_C = 2kΩ, beta = 120, and I_B = 20µA, calculate the maximum possible V_out.

   Hint

   Remember to consider the direction of current flow for voltage polarity.

6. 6.

   Discuss how a change in temperature influences beta and subsequently the signal output in a real amplifier.

   Hint

   Consider how `beta` affects both the input and output currents.