Transistor Biasing and Small-Signal Analysis Essentials Quiz

This quiz assesses your understanding of fundamental concepts in transistor biasing and small-signal analysis for both BJTs and MOSFETs. Choose the best answer for each question to test your foundational knowledge.

1. BJT Biasing Method

   Which biasing method in a BJT circuit uses a resistor divider to set the base voltage for better stability?

   1. Collector feedback bias
   2. Self-biasing
   3. Current mirror bias
   4. Emitter follower bias
   5. Voltage divider bias

2. MOSFET Operating Region

   A MOSFET operates in the saturation region when which condition is true for a typical enhancement-mode NMOS (with respect to Vgs and Vds)?

   1. Vds = 0
   2. Vds u003C Vgs - Vth
   3. Vds u003E Vgs - Vth
   4. Vgs u003C Vth
   5. Vgs = Vds

3. Purpose of Emitter Resistor

   In a common-emitter BJT amplifier, what is the main purpose of including an emitter resistor?

   1. It boosts the input capacitance
   2. It acts as a base resistor
   3. It reduces output impedance to zero
   4. It increases collector resistance
   5. It stabilizes the bias point against temperature variations

4. Small-Signal Model Element

   In the small-signal model of a BJT, what does the parameter 'r_pi' represent?

   1. Collector capacitance
   2. Emitter current gain
   3. Base inductor
   4. Base-to-emitter resistance
   5. Output conductance

5. MOSFET Biasing

   Which component is commonly used to establish the gate voltage in an n-channel MOSFET bias circuit?

   1. Gate resistor divider
   2. Current source at source terminal
   3. Collector bypass capacitor
   4. Base resistor
   5. Emitter-follower

6. Common-Source Amplifier

   In a common-source MOSFET amplifier, what is the primary function of the source bypass capacitor?

   1. To block DC from the drain
   2. To couple AC to the gate
   3. To decrease the input impedance
   4. To set the DC bias
   5. To increase voltage gain by bypassing source resistor at AC

7. BJT Small-Signal Output Resistance

   What is the typical symbol for representing output resistance in the small-signal model for a BJT?

   1. re
   2. rb
   3. ro
   4. rπ
   5. rc

8. Quiescent Point Definition

   The 'quiescent point' (Q-point) in transistor amplifiers refers to which of the following?

   1. The DC operating point with no input signal
   2. The zero-bias emitter voltage
   3. The input at maximum distortion
   4. The highest output voltage
   5. The saturation region edge

9. Source Degeneration

   Adding a resistor in series with the source of a MOSFET amplifier is known as what, and what does this achieve?

   1. Emitter bypassing; reduces input resistance
   2. Gate feedback; increases distortion
   3. Drain division; increases frequency
   4. Source degeneration; increases linearity and stability
   5. Source inversion; lowers gain

10. Beta Stability in BJTs

    Why is it important to design a BJT bias circuit that is relatively insensitive to variations in beta (β)?

    1. To maximize collector voltage swing
    2. Because beta is always constant for one device
    3. To ensure beta decreases with frequency
    4. Because beta can vary significantly between devices and with temperature
    5. So the amplifier does not need a bypass capacitor