DAC output integrity: are “incorrect codes” an error type? In digital-to-analog converters (DACs), various nonideal behaviors affect accuracy. Evaluate the statement: “Incorrect codes are a form of output error for a DAC.” Choose the best assessment.

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
A DAC converts a digital input code to a proportional analog output. Ideal DACs are monotonic and produce exactly the expected analog level for each input code. In practice, several error mechanisms exist, including offset, gain, differential/integral nonlinearity, glitch impulse, and sometimes outright incorrect codes being output due to logic faults or timing issues.



Given Data / Assumptions:

  • “Incorrect codes” refers to the DAC producing an output corresponding to a digital word different from the intended input (e.g., bit errors, metastability, latch timing errors).
  • We are assessing whether such occurrences are considered an output error.
  • Technology-agnostic (applies to binary-weighted, R–2R ladder, and segmented DACs).


Concept / Approach:
Any discrepancy between the intended code-to-output mapping and the actual analog output is an error. If internal logic or interface timing causes the DAC to momentarily or persistently interpret the wrong digital code (or output glitches that correspond to unintended codes), the resulting voltage/current departs from the correct value. Therefore, “incorrect codes” is legitimately a form of output error classification, even if its root cause is digital rather than analog.



Step-by-Step Solution:

Define ideal mapping: code → precise analog level via transfer function.Identify deviation: wrong code selected or latched → wrong analog level.Conclude: this is an output error from the system perspective.Note: mitigation includes input latching, setup/hold adherence, and error detection.


Verification / Alternative check:
Datasheets and application notes often discuss “code errors,” missing codes, and glitch energy—each impacting output fidelity.



Why Other Options Are Wrong:

Incorrect: contradicts the definition of output accuracy.Indeterminate: while details help diagnose, classification as an output error remains valid.Only applies to flash DACs: not true; any DAC can manifest code errors.


Common Pitfalls:
Confusing “code errors” with static nonlinearity alone; code errors can be dynamic or digital-interface-related.



Final Answer:
Correct

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