**Digital to Analog and Analog to Digital Converters Interview Questions and Answers:**

**1. Why conversion of an analog signal into an equivalent digital signal is essential?**

**Ans.** Because most sensors have analog output while much data processing is accomplished with digital computers, analog-to-digital conversion is essential.

**2. What is digital-to-analog conversion?**

**Ans.** Basically, D/A conversion is the process of taking a value represented in digital code (such as simply binary or BCD) and converting it into a voltage or current which is proportional to the digital value.

**3. What is A/D conversion?**

**Ans.** The A/D conversion is the process of converting an analog input voltage into an equivalent digital signal.

**4. Why an A/D converter is usually considered as an encoder?**

**Ans.** A/D converter is usually considered as an encoder as it is used for encoding analog signals for entry into digital system.

**5. Mention the various types of analog to digital converters in the increasing order of speed of Operation.**

**Ans.** A/D converters in the increasing order of speed of operation is given as dual slope type, successive approximation type, parallel-comparator type.

**6. Arrange the following A/D converter in order of increasing speed of operation. ****(i) Successive approximation (ii) Dual slope (iii) Flash (iv) Single slope.**

**Ans.** A/D converters in order of increasing speed of operation are: Dual slope, single slope, successive approximation and flash type.

**7. Give the advantages and disadvantages of an integrating type A to D converters under the following heads: ****(i) speed of operation (ii) change in R-C values (iii) presence of periodic noise (iv) offset voltage of the op-amp.**

Ans.

- Speed of operation — Slow.
- Change in R-C values — The accuracy of this converter is independent of R-C values or any change in them.
- Presence of periodic noise — This converter is very less sensitive to periodic noise.
- Offset voltage of op-amp — Accuracy depends upon the offset values, therefore, the reference voltage should be precise.

**8. What are the advantages of integrating type A/D converters over the non-integrating type?**

**Ans.** The integrating type ADC has the following advantages:

- It is relatively simple and inexpensive.
- Conversion accuracies obtainable are very good.
- Capacitors and resistors need not have high precision.
- Errors due to propagation delay times are eliminated.
- Accuracy depends only on the stability of the reference voltage V
_{REF}. - The comparator offset voltage and current are automatically compensated as the input signals cross zero voltage twice.

**9. What is resolution for a DAC?**

**Ans.** Resolution of a DAC defines the smallest increment in the voltage that can be discerned. Resolution is primarily a function of the number of bits in the digital input signal i.e. the smallest increment output voltage is determined by the LSB.

**10. What is the maximum conversion time for successive approximation ADC?**

**Ans.** The maximum conversion time for successive approximation type ADC is nT_{c} where n is the number of bits and T_{c} is the time period of one clock pulse.