27.8.1. Changes in Input and Output Resistance

Try these first

1. 1.

   What does g_m represent in a transistor?

   Hint

   Think about the relationship between input voltage and output current.

2. 2.

   How does increasing R_E affect voltage gain?

   Hint

   Recall the formula for gain A.

3. 3.

   What happens to the voltage gain as R_E increases?

   • It increases
   • It decreases
   • It remains the same

   Hint

   Think of the gain formula.

4. 4.

   True or False: A larger emitter resistor improves voltage gain.

   • True
   • False

   Hint

   Recall how emitter resistance plays into the gain calculation.

5. 5.

   You have a transistor with a transconductance of 15 mA/V, collector resistance of 1 kΩ, and you want to keep the emitter resistor as high as possible while maintaining a gain of -10. What is the maximum allowed value of R_E?

   Hint

   Focus on rearranging the gain equation to isolate R_E.

6. 6.

   For the circuit with β = 200 and an input resistance of 2 kΩ, find R_E if r_pi = 100Ω. What implications does this have for overall circuit stability?

   Hint

   Calculate R_E's impact on stability.