Digital Electronics Set 2

Electrical Engineering,

Bachelor of Science in Computer Science FY (BSc CS),

Bachelor of Computer Applications (BCA),

Bachelor of Science in Computer Science (BSc CS)

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This set of Digital Electronics Multiple Choice Questions & Answers (MCQs) focuses on Digital Electronics Set 2

Q1 | Which type of gate can be used to add two bits?
  • ex-or
  • ex-nor
  • ex-nand
  • nor
Answer: ex-or
Q2 | Show from the truth table how an exclusive-OR gate can be used to invert the data on one input if the other input is a special control function.
  • using a as the control, when a = 0, x is the same as b. when a = 1, x is the same as b.
  • using a as the control, when a = 0, x is the same as b. when a = 1, x is the inverse of b.
  • using a as the control, when a = 0, x is the inverse of b. when a = 1, x is the same as b.
  • using a as the control, when a = 0, x is the inverse of b. when a = 1, x is the inverse of b.
Answer: using a as the control, when a = 0, x is the same as b. when a = 1, x is the inverse of b.
Q3 | In a flash analog-to-digital converter, the output of each comparator is connected to an input of a ________.
  • decoder
  • priority encoder
  • multiplexer
  • demultiplexer
Answer: priority encoder
Q4 | Which term applies to the maintaining of a given signal level until the next sampling?
  • holding
  • aliasing
  • shannon frequency sampling
  • stair-stepping
Answer: holding
Q5 | An op-amp has very ________.
  • high voltage gain
  • high input impedance
  • low output impedance
  • all of the above
Answer: all of the above
Q6 | The dual-slope analog-to-digital converter finds extensive use in ________.
  • digital voltmeters
  • function generators
  • frequency counters
  • all of the above
Answer: all of the above
Q7 | The ADC0804 is an example of a ________.
  • single-slope analog-to-digital converter
  • dual-slope analog-to-digital converter
  • digital-ramp analog-to-digital converter
  • successive-approximation analog-to-digital converter
Answer: successive-approximation analog-to-digital converter
Q8 | In a digital representation of voltages using an 8-bit binary code, how many values can be defined?
  • 16
  • 64
  • 128
  • 256
Answer: 256
Q9 | A 4-bit R/2R ladder digital-to-analog converter uses ________.
  • one resistor value
  • two resistor values
  • three resistor values
  • four resistor values
Answer: two resistor values
Q10 | A binary-weighted-input digital-to-analog converter has a feedback resistor, Rf, of 12 k. If 50 A of current is through the resistor, voltage out of the circuit is ________.
  • 0.6 v
  • –0.6 v
  • 0.1 v
  • –0.1 v
Answer: –0.6 v
Q11 | The resolution of a 6-bit DAC is ________.
  • 63%
  • 64%
  • 15.9%
  • 1.59%
Answer: 1.59%
Q12 | How are unwanted frequencies removed prior to digital conversion?
  • pre-filters
  • digital signal processing
  • sample-and-hold circuits
  • all of the above
Answer: pre-filters
Q13 | Which type of programming is typically used for digital signal processors?
  • assembly language
  • machine language
  • c
  • none of the above
Answer: assembly language
Q14 | Which of the following best defines Nyquist frequency?
  • the frequency of resonance for the filtering circuit
  • the second harmonic
  • the lower frequency limit of sampling
  • the highest frequency component of a given analog signal
Answer: the highest frequency component of a given analog signal
Q15 | Which is not an A/D conversion error?
  • differential nonlinearity
  • missing code
  • incorrect code
  • offset
Answer: differential nonlinearity
Q16 | Settling time is normally defined as the time it takes a DAC to settle within ________.
  • 1/8 lsb of its final value when a change occurs in the input code
  • 1/4 lsb of its final value when a change occurs in the input code
  • 1/2 lsb of its final value when a change occurs in the input code
  • 1 lsb of its final value when a change occurs in the input code
Answer: 1/2 lsb of its final value when a change occurs in the input code
Q17 | Determine the output frequency for a frequency division circuit that contains 12 flip-flops with an input clock frequency of 20.48 MHz.
  • 10.24 khz
  • 5 khz
  • 30.24 khz
  • 15 khz
Answer: 5 khz
Q18 | Which statement BEST describes the operation of a negative-edge-triggered D flip-flop?
  • the logic level at the d input is transferred to q on ngt of clk.
  • the q output is always identical to the clk input if the d input is high.
  • the q output is always identical to the d input when clk = pgt.
  • the q output is always identical to the d input.
Answer: the logic level at the d input is transferred to q on ngt of clk.
Q19 | Propagation delay time, tPLH, is measured from the ________.
  • triggering edge of the clock pulse to the low-to-high transition of the output
  • triggering edge of the clock pulse to the high-to-low transition of the output
  • preset input to the low-to-high transition of the output
  • clear input to the high-to-low transition of the output
Answer: triggering edge of the clock pulse to the low-to-high transition of the output
Q20 | How is a J-K flip-flop made to toggle?
  • j = 0, k = 0
  • j = 1, k = 0
  • j = 0, k = 1
  • j = 1, k = 1
Answer: j = 1, k = 1
Q21 | How many flip-flops are in the 7475 IC?
  • 1
  • 2
  • 4
  • 8
Answer: 4
Q22 | How many flip-flops are required to produce a divide-by-128 device?
  • 1
  • 4
  • 6
  • 7
Answer: 7
Q23 | The ________ circuit overcomes the problem of switching caused by jitter on the inputs.
  • astable multivibrator
  • monostable multivibrator
  • bistable multivibrator
  • schmitt trigger
Answer: schmitt trigger
Q24 | Why would a delay gate be needed for a digital circuit?
  • a delay gate is never needed.
  • to provide for setup times
  • to provide for hold times
  • to provide for setup times and hold times
Answer: to provide for setup times and hold times
Q25 | A Schmitt trigger has VT+ = 2.0 V and VT– = 1.2 V. What is the hysteresis voltage of the Schmitt trigger?
  • 0.4 volt
  • 0.6 volt
  • 0.8 volt
  • 1.2 volts
Answer: 0.8 volt
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