19.1.3. Transconductance and Its Definition

Try these first

1. 1.

   What is the definition of transconductance?

   Hint

   Think about the formula ΔI_C/ΔV_BE.

2. 2.

   What does the term Q-point refer to?

   Hint

   Connect it to the concept of biasing in circuits.

3. 3.

   What does transconductance measure?

   • The change in collector voltage with respect to base-emitter voltage.
   • The change in collector current with respect to base-emitter voltage.
   • The change in base current with respect to collector current.

   Hint

   Think about what input and output parameters transconductance relates.

4. 4.

   True or False: Higher transconductance means better amplification capability.

   • True
   • False

   Hint

   Relate it to circuit design impacts.

5. 5.

   If you have a transistor with a transconductance of 5 mA/V and a Q-point at which the I_C is 10 mA, how much will I_C change for a 40 mV increase in V_BE?

   Hint

   Apply the transconductance definition to calculate the rise in current.

6. 6.

   A circuit with a transistor has output conductance g_o equal to 2 mS. What is the output resistance, and how does this relate to transconductance in circuits?

   Hint

   Use the resistive properties of conductance to derive output resistance.