DIGITAL ELECTRONICS
Branch: Electrical Engg. (Electronics and Power)
Unit iv: A/D and D/A Converters (MCQ’s)
1.How many control lines are present in analog to digital converter in addition to
reference voltage?
a) Three
b) Two
c) One
d) None of the mentioned
Correct answer is b
2. Find out the integrating type analog to digital converter?
a) Flash type converter
b) Tracking converter
c) Counter type converter
d) Dual slope ADC
Correct answer is d
3. Which type of ADC follow the conversion technique of changing the analog
input signal to a linear function of frequency?
a) Direct type ADC
b) Integrating type ADC
c) Both integrating and direct type ADC
d) None of the mentioned
Correct answer is b
4. Which A/D converter is considered to be simplest, fastest and most expensive?
a) Servo converter
b) Counter type ADC
c) Flash type ADC
d) All of the mentioned
Correct answer is c
5. The flash type A/D converters are called as
a) Parallel non-inverting A/D converter
b) Parallel counter A/D converter
c) Parallel inverting A/D converter
d) Parallel comparator A/D converter
Correct answer is d
6. What is the advantage of using flash type A/D converter?
a) High speed conversion
b) Low speed conversion
c) Nominal speed conversion
d) None of the mentioned
Correct answer is a
7. The number of comparator required for flash type A/D converter
a) Triples for each added bit
b) Reduce by half for each added bit
c) Double for each added bit
d) Doubles exponentially for each added bit
Correct answer is c
8. Drawback of counter type A/D converter
a) Counter clears automatically
b) More complex
c) High conversion time
d) Low speed
Correct answer is d
9. Calculate the conversion time of a 12-bit counter type ADC with 1MHz clock
frequent to convert a full scale input?
a) 4.095 µs
b) 4.095ms
c) 4.095s
d) None of the mentioned
Correct answer is b
10. In a servo tracking A/D converter, the input voltage is greater than the DAC
output signal at this condition
a) The counter count up
b) The counter count down
c) The counter back and forth
d) None of the mentioned
Correct answer is a
11. At what condition error occurs in the servo tracking A/D Converter?
a) Slow change input
b) Rapid change in input
c) No change in input
d) All of the mentioned
Correct answer is b
12. How many clock pulses do a successive approximation converter requires for
obtaining a digital output.
a) Twelve
b) Six
c) Eight
d) None of the mentioned
Correct answer is d
13. Which of the following should be done in order to convert a continuous-time
signal to a discrete-time signal?
a) Sampling
b) Differentiating
c) Integrating
d) None of the mentioned
Correct answer is a
14. The process of converting discrete-time continuous valued signal into discretetime discrete valued (digital) signal is known as ____________
a) Sampling
b) Quantization
c) Coding
d) None of the mentioned
Correct answer is b
15. The difference between the unquantized x(n) and quantized xq(n) is known as
___________
a) Quantization coefficient
b) Quantization ratio
c) Quantization factor
d) Quantization error
Correct answer is d
16. Which of the following is a digital-to-analog conversion process?
a) Staircase approximation
b) Linear interpolation
c) Quadratic interpolation
d) All of the mentioned
Correct answer is d
17. The relation between analog frequency ‘F’ and digital frequency ‘f’ is?
a) F=f*T(where T is sampling perioD.
b) f=F*T
c) No relation
d) None of the mentioned
Correct answer is b
18. What is the output signal when a signal x(t)=cos(2*pi*40*t) is sampled with a
sampling frequency of 20Hz?
a) cos(pi*n)
b) cos(2*pi*n)
c) cos(4*pi*n)
d) cos(8*pi*n)
Correct answer is c
19. If ‘F’ is the frequency of the analog signal, then what is the minimum sampling
rate required to avoid aliasing?
a) F
b) 2F
c) 3F
d) 4F
Correct answer is a
20. What is the Nyquist rate of the signal x(t)=3cos(50*pi*t)+10sin(300*pi*t)cos(100*pi*t)?
a) 50Hz
b) 100Hz
c) 200Hz
d) 300Hz
Correct answer is d
21. What is the discrete-time signal obtained after sampling the analog signal
x(t)=cos(2000*pi*t)+sin(5000*pi*t) at a sampling rate of 5000 samples/sec?
a) cos(2.5*pi*n)+sin(pi*n)
b) cos(0.4*pi*n)+sin(pi*n)
c) cos(2000*pi*n)+sin(5000*pi*n)
d) none of the mentioned
Correct answer is b
22. If the sampling rate Fs satisfies the sampling theorem, then the relation
between quantization errors of the analog signal(eq(t)) and discrete-time
signal(eq(n)) is?
a) eq(t)=eq(n)
b) eq(t)<eq(n)
c) eq(t)>eq(n)
d) not related
Correct answer is a
Unit v: Semiconductor memories (MCQ’s)
1) Which among the following ROMs exhibit/s the necessity of eliminating the
PROM from the circuit?
a. EPROM
b. EEPROM
c. Both a and b
d. None of the above
Correct answer is a
2) Which signal is used to transfer the stored data into RAM?
a. Store
b. Load
c. Recall
d. Move
Correct answer is c
3) Which components play a significant role in the formation of a dynamic RAM?
a. Two MOSFETs
b. Two capacitors
c. One MOSFET and one capacitor
d. One MOSFET and two capacitors
Correct answer is c
4) What is the bit storage capacity of TTL RAM cell?
a. 0
b. 1
c. 4
d. 16
Correct answer is d
5) With the availability of 16 x 4 memory size, how many ICs ( memory chips)
will be required for the expansion of its word size in order to obtain 16 x 8
memory?
a. 2
b. 4
c. 8
d. 16
Correct answer is a
6) Which parameter of read cycle timing characteristics defines the maximum
time delay between the beginning of read pulse and output buffers arriving at
active state from Hi-z condition?
a. Read to output valid time
b. Read to output active time
c. Access time
d. Output tristate from read time
Correct answer is b
7) Which among the following specifies the minimum amount of time necessary
for data validation after the termination of the write pulse?
a. Write pulse time
b. Write release time
c. Data set up time
d. Data hold up time
Correct answer is d
8) Which among the following techniques is used by EPROM for erasing
purpose?
a. Force Convection
b. Ultraviolet Radiation
c. Photo-conduction
d. None of the above
Correct answer is b
9) Which operations are likely to get performed by the Content Accessible
Memories (CAM) in addition to read/write operations executed by conventional
memories?
a. Association
b. Distribution
c. Commutation
d. Identification
Correct answer is a
10) Which among the following memories utilizes the electrical voltage for
erasing purposes?
a. PROM
b. EAROM
c. RAM
d. CAM
Correct answer is b