65.1.6. Input Capacitance Calculation

Try these first

1. 1.

   What is the voltage gain of the discussed cascode amplifier?

   Hint

   Recall the earlier calculations in the session.

2. 2.

   Define input capacitance in the context of an amplifier.

   Hint

   Think about what capacitance affects in a circuit.

3. 3.

   What does the input capacitance depend on in a cascode amplifier?

   • Voltage gain
   • Load resistance
   • Both A and B

   Hint

   Consider how modifications in gain and resistance interplay.

4. 4.

   True or False: Higher gain in a cascode amplifier always results in a higher input capacitance.

   • True
   • False

   Hint

   Remember the relationship defined in the section.

5. 5.

   Given a cascode amplifier with C_gs1 = 12 pF and C_gd1 = 7 pF and a voltage gain of -40, calculate the new input capacitance.

   Hint

   Substitue the values carefully into the formula.

6. 6.

   Investigate how changing small-signal parameters affects both gain and capacitance in the circuit if you switch from using MOSFETs to BJTs.

   Hint

   Research the inherent differences between BJTs and MOSFETs to support your analysis.