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Unit 4: Fundamentals of semiconductor devices and digital circuits - Practice Quiz

ECE131 — Basic Electrical And Electronics Engineering 50 Questions
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1 Which of the following best describes the 'Digital Abstraction' in electronic circuits?

A. Operating circuits solely at .
B. Using only inductors and capacitors to process signals.
C. Treating signals as continuous variables with infinite precision.
D. Discretizing continuous analog signals into specific logic levels to ignore noise.

2 According to the static discipline, if a digital system specifies a valid output high voltage range and a valid input high voltage range , which relationship must hold true to ensure noise immunity?

A.
B.
C.
D.

3 What is the forbidden region in the context of digital voltage levels?

A. The region where current is zero.
B. The voltage range between and where logic state is undefined.
C. The voltage range below .
D. The voltage range above .

4 Which Boolean algebra law is represented by the equation ?

A. Commutative Law
B. De Morgan's Law
C. Associative Law
D. Distributive Law

5 Identify the logic gate that produces a High (1) output only when both inputs are Low (0).

A. AND
B. NOR
C. XOR
D. NAND

6 Which of the following sets of gates are known as Universal Gates?

A. XOR, XNOR
B. AND, OR
C. NOT, BUFFER
D. NAND, NOR

7 The Fan-out of a logic gate is defined as:

A. The delay time between input and output.
B. The maximum number of standard logic inputs that the output of the gate can drive reliably.
C. The power dissipated by the gate.
D. The number of inputs the gate possesses.

8 If the Fan-in of a logic gate is increased excessively, what is the likely physical consequence on the input stage?

A. The gate becomes an inductor.
B. The voltage levels invert.
C. The noise margin becomes infinite.
D. Input capacitance increases, increasing propagation delay.

9 Calculate the Noise Margin High () given: , , , and .

A.
B.
C.
D.

10 Which formula correctly represents Noise Margin Low ()?

A.
B.
C.
D.

11 In a voltage transfer characteristic (VTC) of a logic gate, what condition implies that the gate has gain and is regenerative?

A. The slope of the VTC is always 0.
B. The maximum slope of the VTC is less than 1.
C. The magnitude of the slope in the transition region is .
D. The input voltage equals the output voltage everywhere.

12 In a PN junction diode under no bias condition, what causes the formation of the depletion region?

A. Diffusion of majority carriers across the junction and subsequent recombination.
B. Drift of minority carriers.
C. External battery voltage.
D. Thermal runaway.

13 Under forward bias, the width of the depletion layer in a PN junction diode:

A. Decreases
B. Increases
C. Vanishes immediately to zero
D. Remains constant

14 The current through a diode is related to the voltage by the Shockley equation: . What is ?

A. Terminal Voltage
B. Thermal Voltage (approx 26mV at room temp)
C. Total Voltage
D. Threshold Voltage

15 What is the typical 'knee' or cut-in voltage for a Silicon diode?

A.
B.
C.
D.

16 Which breakdown mechanism occurs in a Zener diode that is heavily doped and operates at low reverse voltages ()?

A. Punch-through
B. Thermal Breakdown
C. Zener Breakdown
D. Avalanche Breakdown

17 What is the primary application of a Zener diode when used in a circuit?

A. Current rectification
B. Signal amplification
C. Oscillation
D. Voltage regulation

18 In a diode I-V characteristic, the Reverse Saturation Current () is primarily due to:

A. Doping concentration
B. Majority carriers
C. Minority carriers generated thermally
D. Forward bias voltage

19 When testing a diode with a multimeter in 'Diode Mode', a good Silicon diode should display approximately what value in forward bias?

A. OL (Open Loop)
B. to (Volts)
C. (Short circuit)
D. to (Volts)

20 A rectifier circuit is used to convert:

A. High voltage to Low voltage
B. DC to AC
C. Current to Voltage
D. AC to DC

21 Identify the three terminals of a Bipolar Junction Transistor (BJT).

A. Anode, Cathode, Gate
B. Base, Emitter, Collector
C. Gate, Source, Drain
D. Input, Output, Ground

22 For a BJT to operate in the Active Region (used for amplification), how must the junctions be biased?

A. Base-Emitter: Reverse, Base-Collector: Forward
B. Base-Emitter: Forward, Base-Collector: Reverse
C. Base-Emitter: Forward, Base-Collector: Forward
D. Base-Emitter: Reverse, Base-Collector: Reverse

23 The parameter (or ) of a BJT is defined as the ratio of:

A. Collector current () to Base current ()
B. Emitter current () to Base current ()
C. Collector current () to Emitter current ()
D. Base current () to Emitter current ()

24 In a BJT, the relationship between Emitter current (), Base current (), and Collector current () is:

A.
B.
C.
D.

25 When a BJT acts as a closed switch (fully ON), in which region is it operating?

A. Breakdown Region
B. Cut-off Region
C. Active Region
D. Saturation Region

26 The input characteristics of a Common Emitter BJT configuration resemble the characteristics of a:

A. Resistor
B. Forward biased diode
C. Reverse biased diode
D. Capacitor

27 What does MOSFET stand for?

A. Metal Organic Semiconductor Field Effect Transistor
B. Magnetic Oxide Silicon Field Effect Transistor
C. Metal Oxide Semiconductor Field Effect Transistor
D. Main Oxide Semiconductor Field Emission Transistor

28 The main advantage of a MOSFET over a BJT is:

A. Very high input impedance
B. Current controlled operation
C. Low input impedance
D. Lower switching speed

29 In an N-Channel Enhancement type MOSFET, current flows between Drain and Source only when:

A. is greater than the Threshold Voltage ()
B.
C. is negative
D. The Gate is left floating

30 The terminals of a MOSFET are named:

A. Anode, Cathode, Gate
B. Gate, Drain, Source, (Body)
C. Base, Emitter, Collector
D. Input, Output, Control

31 Which equation describes the drain current of a MOSFET in the saturation region?

A.
B.
C.
D.

32 What is ESD in the context of handling Integrated Circuits (ICs)?

A. Electrostatic Discharge
B. Electronic System Design
C. Electric Signal Distortion
D. Energy Saving Device

33 Why are MOSFET-based ICs (CMOS) particularly susceptible to ESD damage?

A. The gate oxide layer is extremely thin and can be punctured by high voltage.
B. They operate at high currents.
C. They are made of plastic.
D. They have thick metal wires.

34 Which of the following is a standard precaution to prevent ESD damage when handling ICs?

A. Wearing wool gloves.
B. Touching the pins of the IC frequently.
C. Handling ICs in a low humidity environment.
D. Using a wrist strap connected to earth ground.

35 The Human Body Model (HBM) simulates ESD events. What is the typical voltage range a human body can accumulate simply by walking across a carpet?

A. Hundreds of thousands of volts
B.
C. Several kilovolts ()
D.

36 In digital logic, an XOR gate with inputs A and B is defined by the equation:

A.
B.
C.
D.

37 A Depletion mode MOSFET is normally:

A. ON (Conducting) at
B. Acting as a capacitor
C. OFF (Non-conducting) at
D. Destroyed at

38 What is the result of the boolean expression ?

A.
B.
C.
D.

39 The dynamic resistance () of a diode is calculated as:

A.
B.
C.
D.

40 A Clamper circuit uses a diode and a capacitor to:

A. Filter high frequencies.
B. Rectify the signal.
C. Shift the DC level of the signal.
D. Clip off parts of the waveform.

41 In BJT testing, if the resistance between Collector and Emitter is low in both directions (swapping probes), the transistor is likely:

A. Good
B. Open
C. High gain
D. Short-circuited

42 Which region of the MOSFET characteristics is used for linear amplification?

A. Saturation (Active)
B. Breakdown
C. Cut-off
D. Linear (Triode/Ohmic)

43 The Truth Table for a 2-input NAND gate is:

A. 00->0, 01->1, 10->1, 11->1
B. 00->1, 01->1, 10->1, 11->0
C. 00->1, 01->0, 10->0, 11->1
D. 00->0, 01->0, 10->0, 11->1

44 What is the effect of increasing temperature on a semiconductor diode?

A. Conductivity decreases.
B. Barrier potential increases.
C. Reverse saturation current decreases.
D. Reverse saturation current increases significantly.

45 Which component is represented by a symbol of a diode with two arrows pointing towards it?

A. Zener Diode
B. Photodiode
C. Schottky Diode
D. LED (Light Emitting Diode)

46 In Digital Logic, a 'Buffer' gate:

A. Always outputs 1.
B. Outputs the same logic state as input but strengthens the signal (current drive).
C. Inverts the signal.
D. Performs an AND operation.

47 For a transistor acting as a switch, the Cut-off state corresponds to:

A. Amplification
B. Logic 0 (Open Circuit / Non-conducting)
C. Short Circuit
D. Logic 1 (High Voltage)

48 Which material is most commonly used in modern Integrated Circuits (ICs) and MOSFETs?

A. Germanium
B. Silicon
C. Copper
D. Gallium Arsenide

49 The Pinch-off voltage () in a JFET or Depletion MOSFET corresponds to:

A. The voltage where the device burns out.
B. The gate voltage at which drain current becomes zero.
C. The forward bias voltage.
D. The drain voltage where saturation begins.

50 What is the value of binary AND ?

A.
B.
C.
D.
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