BEE Semiconductor Devices and Circuits 4

Question 1

What is the effect of increasing temperature on the reverse saturation current IS of a p-n junction diode?

Accepted Answer

IS increases approximately doubling every 10°C

Answer

Reverse saturation current approximately doubles for every 10°C rise in temperature due to increased minority carrier generation.

Question 2

In a common-emitter BJT amplifier, adding an unbypassed emitter resistor RE primarily:

Accepted Answer

Stabilizes the Q-point and increases input impedance but reduces voltage gain

Answer

An unbypassed RE provides negative feedback that stabilizes bias, raises input impedance, but reduces the voltage gain from −RC/re to approximately −RC/RE.

Question 3

The output resistance of an ideal op-amp is:

Accepted Answer

Zero

Answer

An ideal op-amp has zero output resistance, meaning it can source or sink any current without a voltage drop.

Question 4

Channel length modulation in a MOSFET is modeled in the saturation region by including which factor in the drain current equation?

Accepted Answer

(1 + λVDS)

Answer

The channel-length modulation factor (1 + λVDS) is multiplied into the saturation current to model the slight increase in ID with VDS.

Question 5

Which breakdown mechanism dominates in a heavily doped p-n junction with a thin depletion region at low reverse voltages?

Accepted Answer

Zener (tunneling) breakdown

Answer

In heavily doped, narrow depletion junctions, quantum mechanical tunneling (Zener effect) dominates at low reverse voltages (typically below 5–6 V).

BEE - Bachelor of Electrical Engineering Practice Test

BEE - Bachelor of Electrical Engineering Practice Test

BEE Semiconductor Devices and Circuits 4