Flash ADC architecture — role of the comparator outputs In a flash analog-to-digital converter, the outputs of the parallel comparators are connected to the inputs of which digital block to produce the final binary code?

Introduction / Context:A flash ADC uses a bank of comparators to compare the input voltage against a ladder of reference levels. The pattern of comparator outputs forms a thermometer code that must be transformed into a binary output quickly and unambiguously.

Given Data / Assumptions:

• Multiple comparators fire in order as input increases.
• The raw comparator outputs constitute a thermometer code (a run of 1s followed by 0s).
• Bubble errors may occur and are handled by encoding logic.

Concept / Approach:The thermometer code is converted to a binary (or Gray) representation by a priority encoder that finds the highest-order active comparator. Additional bubble-correction logic may precede encoding to clean up isolated errors.

Step-by-Step Solution:Comparators compare Vin to ladder taps.Outputs → thermometer code vector.Priority encoder selects the highest asserted comparator to generate binary code.

Verification / Alternative check:Block diagrams in datasheets show comparator array feeding a priority encoder (sometimes with pre-encode correction).

Why Other Options Are Wrong:

• Decoder/demux: Translate a code to many lines; inverse of what is required.
• Multiplexer: Selects one of many signals; not encoding thermometer patterns.

Common Pitfalls:Confusing thermometer-to-binary conversion with general decoding; the correct block is a priority encoder.

Final Answer:priority encoder