Linear Integrated Circuit Multiple Choice Questions on ” A to D Converter -1″.
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
Answer: B
Clarification: ADC usually has two additional control lines
1. Start input-tell ADC when to start conversion.
2. EOC- end of conversion.
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
Answer: D
Clarification: Other than dual slope ADC the rest belongs to direct type ADCs.
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
Answer: B
Clarification: 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.
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
Answer: C
Clarification: The simplest possible A/D converter is flash type converter and is expensive for high degree of accuracy.
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
Answer: D
Clarification: The flash type A/D converter are also called as parallel comparator A/D converter because the purpose of the circuit is to compare the analog input voltage with each node voltage.
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
Answer: A
Clarification: Flash type ADC has the advantage of high speed as the conversion takes place simultaneously rather than sequentially. Typical conversion time is 100nanosecond or less.
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
Answer: C
Clarification: The number of comparator 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.
8. Drawback of counter type A/D converter
A. Counter clears automatically
B. More complex
C. High conversion time
D. Low speed
Answer: D
Clarification: In counter type ADC counter frequency is kept low enough to give sufficient time for DAC to settle and for the comparator for respond. So, low speed is the most serious drawback.
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