Reducing quantization error in ADC systems How can quantization error be reduced in a counter-type or similar analog-to-digital converter architecture?
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Aincreasing the number of bits in the counter and DAC.
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Bdecreasing the number of bits in the counter and increasing the number of bits in the DAC.
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Cincreasing the number of bits in the counter and decreasing the number of bits in the DAC.
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Ddecreasing the number of bits in the counter and DAC.
Answer
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.