25.3.3. Solutions to Instability Problems

Try these first

1. 1.

   What effect does an increase in beta have on the collector current?

   Hint

   Consider how beta relates to collector and base currents.

2. 2.

   What is the main purpose of an emitter resistor in a CE amplifier?

   Hint

   Think about negative feedback mechanisms.

3. 3.

   What happens to the Q-point if beta increases significantly?

   • It remains stable
   • It shifts towards saturation
   • It cannot be determined

   Hint

   Consider the relationship between beta and collector current.

4. 4.

   True or False: A bypass capacitor allows DC signals to pass while blocking AC signals.

   • True
   • False

   Hint

   Think about the function of a bypass capacitor.

5. 5.

   Given a CE amplifier with known parameters, calculate the impact on the Q-point if the temperature changes, and reevaluate the optimal design with an emitter resistor.

   Hint

   Use characteristic curves and stability diagrams for support.

6. 6.

   Critique a given amplifier design for susceptibility to thermal runaway, providing modifications.

   Hint

   Look at both the thermal effects and the AC analysis of the amplifier.