Fastest ADC architecture comparison Evaluate the statement: “The flash (parallel) converter is the fastest analog-to-digital conversion method used in practice.”

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
ADC architectures trade off speed, resolution, power, and area. Flash converters prioritize speed by performing all threshold comparisons in parallel, minimizing latency to only comparator and encoding delays.



Given Data / Assumptions:

  • Flash ADC uses 2^N - 1 comparators for N bits.
  • Architectures like SAR, pipeline, and sigma-delta have sequential elements that add latency.
  • We compare maximum achievable sampling rates at modest resolutions (commonly up to 8 bits for flash).


Concept / Approach:
Parallel operation eliminates per-bit decision cycles. While pipeline ADCs can be very fast at higher resolutions, pure latency and per-sample decision time remain lowest for flash designs, making them the fastest for moderate resolutions.



Step-by-Step Solution:

Assess comparator array and encoder delay paths.Compare with SAR (binary search per sample) and pipeline (stage-by-stage) latencies.Conclude that parallel comparison gives the shortest conversion time.Note practical limits: power and area grow exponentially with resolution.


Verification / Alternative check:
Survey datasheets: the highest per-channel sample rates at low-to-moderate resolution are flash or time-interleaved flash.



Why Other Options Are Wrong:
“Incorrect” ignores widespread practice. The other statements add conditions not required for the general conclusion.



Common Pitfalls:
Confusing maximum sample rate with resolution; overlooking power/area trade-offs; forgetting encoder bubble suppression.



Final Answer:
Correct

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