BEE Semiconductor Devices and Circuits 2

Question 1

In a MOSFET, the threshold voltage VT is most directly affected by which parameter?

Accepted Answer

Gate oxide thickness

Answer

Threshold voltage is directly related to oxide capacitance, which depends on gate oxide thickness (VT increases as tox increases).

Question 2

A zener diode is operated in reverse breakdown with VZ = 6.2 V and IZ = 20 mA. What power must it dissipate?

Accepted Answer

124 mW

Answer

Power = VZ × IZ = 6.2 V × 20 mA = 124 mW.

Question 3

Which biasing configuration gives a BJT the highest input impedance?

Accepted Answer

Common collector

Answer

The common-collector (emitter-follower) configuration exhibits the highest input impedance among standard BJT configurations.

Question 4

What is the primary function of the depletion region in a p-n junction?

Accepted Answer

It creates a built-in electric field that opposes further diffusion

Answer

The depletion region's ionized dopant atoms create a built-in electric field that counters carrier diffusion, establishing equilibrium.

Question 5

In the early effect (base-width modulation) of a BJT, increasing VCE causes the collector current to:

Accepted Answer

Increase slightly due to narrowing of the base

Answer

Increasing VCE widens the collector-base depletion region, narrowing the base and increasing the collector current gradient.

BEE - Bachelor of Electrical Engineering Practice Test