D-A and A-D Converter MCQ [Free PDF] - Objective Question Answer for D-A and A-D Converter Quiz

21. 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

Answer: B

ADC usually has two additional control lines
1. Start input-tell ADC when to start conversion.
2. EOC- end of conversion.

22. Find out the integrating type of analog to the digital converter?

A. Flash-type converter
B. Tracking converter
C. Counter type converter
D. Dual slope ADC

Answer: D

Other than dual-slope ADC the rest belongs to direct type ADCs.

23. Which type of ADC follows 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

Answer: B

Integrating type ADC performs conversion in an indirect manner by first changing the analog input signal to a linear function of time or frequency and then to a digital code.

24. 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

Answer: C

The simplest possible A/D converter is flash type converter and is expensive for a high degree of accuracy.

25. 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

Answer: D

The flash type A/D converter is also called a parallel comparator A/D converter because the purpose of the circuit is to compare the analog input voltage with each node voltage.

26. What is the advantage of using a flash-type A/D converter?

A. High-speed conversion
B. Low-speed conversion
C. Nominal speed conversion
D. None of the mentioned

Answer: A

Flash type ADC has the advantage of high speed as the conversion takes place simultaneously rather than sequentially. The typical conversion time is 100nanosecond or less.

27. The number of comparators 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

Answer: C

The number of comparators required almost doubles for each added bit. For example – 2 -bit ADC requires three comparators, 3 -bit ADC needs seven comparators, and a 4 -bit ADC requires fifteen comparators.

28. Drawback of counter type A/D converter

A. Counter clears automatically
B. More complex
C. High conversion time
D. Low speed

Answer: D

In counter type, ADC counter frequency is kept low enough to give sufficient time for DAC to settle and for the comparator to respond. So, low speed is the most serious drawback.

29. Calculate the conversion time of a 12-bit counter-type ADC with 1MHz clock frequency to convert a full-scale input?

A. 4.095 µs
B. 4.095ms
C. 4.095s
D. None of the mentioned

Answer: B

Conversion time 12-bit counter-type ADC

= 2ⁿ -1 clock periods

= (12ⁿ-1) = 4.095ms.

30. In a servo tracking A/D converter, the input voltage is greater than the DAC output signal at this condition

A. The counter counts up
B. The counter count down
C. The counter back and forth
D. None of the mentioned

Answer: A

In the servo converter, the circuit consists of an up/down counter with a comparator controlling the direction of the count. So, if the input voltage is greater than the DAC output signal, the output of the comparator goes high and the counter is caused to count up.

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