Digital-to-Analog converters: “Incorrect codes” are not an output error mode of a DAC; DAC output errors are measured as analog inaccuracies (offset, gain, DNL, INL), not digital code errors on the output.

Difficulty: Medium

Correct Answer: Incorrect

Explanation:


Introduction / Context:
A DAC accepts digital input codes and produces an analog output (voltage or current). This question checks conceptual clarity: where do “errors” manifest for a DAC—on a digital code line or as an analog deviation?


Given Data / Assumptions:

  • A DAC input is a digital code; its output is analog.
  • Common DAC error metrics: offset error, gain error, differential nonlinearity (DNL), integral nonlinearity (INL), missing codes, and sometimes glitch impulse.
  • “Incorrect codes” would imply an erroneous digital value on a DAC output, which does not exist because the DAC outputs an analog signal.


Concept / Approach:
DAC performance is evaluated by comparing the actual analog output to the ideal output for a given input code. Any discrepancy is an analog error. If an upstream digital block generates the wrong input code, that is a system-level digital error, not an intrinsic DAC “output error.”


Step-by-Step Solution:
Define DAC output: analog quantity driven by a digital input code.List analog-centric error terms (offset, gain, DNL, INL).Conclude “incorrect codes” describes a digital-input issue, not an analog-output error type.


Verification / Alternative check:
Check a DAC datasheet: error specifications are analog deviations (in LSB or percent of full scale), not “wrong digital codes” at the output.


Why Other Options Are Wrong:
Limiting to current-output DACs or ideal references misses the core idea. Load resistor affects accuracy but does not change the definition of error domains.


Common Pitfalls:
Confusing ADC “code errors” (digital output) with DAC, whose output domain is analog.


Final Answer:
Incorrect

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