Understanding Flash Type ADC
A flash ADC (Analog-to-Digital Converter) is known for its speed and simplicity. It converts an analog voltage to a digital code in a single step, using multiple comparators.
Components of a 3-bit Flash ADC
To design a 3-bit flash ADC, we need to determine the number of comparators and the number of resistors required.
Number of Comparators
- For an n-bit ADC, the number of output levels is 2^n.
- Hence, for a 3-bit ADC, there are 2^3 = 8 output levels.
- To determine the number of comparators required, we use the formula: Number of Comparators = 2^n - 1.
- For 3 bits: 2^3 - 1 = 7 comparators.
Resistor Ladder Network
To create the reference voltage levels for the comparators, a resistor ladder is employed. The resistor ladder divides the reference voltage into equal parts.
Number of Resistors Required
- For n-bit ADCs, the number of resistors needed in the ladder is equal to the number of comparators.
- Therefore, for 7 comparators, we need 7 resistors.
- However, the resistor ladder will have 1 additional resistor to create the last reference voltage.
- Thus, the total number of resistors needed is 7 + 1 = 8.
Conclusion
- Therefore, the correct answer for the number of standard resistors required to design a 3-bit flash type ADC is 8 (Option C).
- This configuration ensures all comparators have appropriate reference levels for accurate conversion.