Reducing quantization error in ADC systems How can quantization error be reduced in a counter-type or similar analog-to-digital converter architecture?

Difficulty: Easy

Correct Answer: increasing the number of bits in the counter and DAC.

Explanation:


Introduction / Context:
Quantization error arises because an ADC can only represent the input with discrete codes. Increasing resolution reduces the LSB size and therefore the quantization step error.



Given Data / Assumptions:

  • Counter-type (or similar) ADC using an internal DAC for comparison.
  • Resolution determined by number of bits N.


Concept / Approach:
The LSB equals full-scale range / 2^N. Quantization error is on the order of ±0.5 LSB for an ideal converter. Increasing N increases 2^N and thus reduces LSB size and error magnitude. Both the counter and DAC must support the higher resolution.



Step-by-Step Solution:

Recognize quantization step ∝ 1 / 2^N.To reduce step size, increase N in both the counter and DAC.Select the option that increases resolution consistently.


Verification / Alternative check:
Example: doubling bits from 8 to 9 halves the LSB, halving quantization error in volts.



Why Other Options Are Wrong:

  • Decrease bits: Makes the LSB larger, increasing error.
  • Mismatched changes: Increasing only one of counter or DAC does not improve system resolution.


Common Pitfalls:

  • Confusing quantization error with noise or linearity; increasing bits specifically addresses quantization.


Final Answer:
increasing the number of bits in the counter and DAC.

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