Question

For a 4-bit Flash type Analog to Digital Convertor (ADC) with full scale input voltage range “V”, which of the following statement(s) is/are true ?
1. The ADC requires 15 comparators.
2. The ADC requires one 4 to 2 priority encoder and 4 comparators.
3. A change in the input voltage by V/16 will always flip MSB of the output.
4. A change in the input voltage by V/16 will always flip the LSB of the output.

Answer 1

Correct Answer - Option :

Flash Type ADC:

• Flash type Analog to Digital converter (ADC) converts the analog signal to digital signal.
• It is the fastest ADC Converter as compare to other ADC.
• A number of comparators used for N-bit Flash type ADC are (2N -1) and, so for 4 bit Flash type ADC will require 15 no. of the comparator.
• Flash type ADC requires (2N × N) priority encoder and 2N no. of the resistor, so for 4-bit flash type ADC requires 16 × 4 priority encoders and 16 resistors.
• Resolution of Flash type ADC is V/(2N) so for 4 bit Flash type ADC  have resolution V/16.
• So if there is a change in input voltage by V/16 it will change the LSB of the output.