DAC behavior definition: A digital-to-analog converter is said to be ________ if its analog output never decreases when the binary input code increments to the next value.

Introduction / Context:
In precision control and measurement systems, a fundamental requirement is that a DAC’s output behaves predictably as the digital input code increases. The formal property that captures this is called monotonicity. Knowing this term helps engineers specify converters correctly for closed-loop applications.

Given Data / Assumptions:

• Input codes increase in standard binary sequence.
• We consider ideal static behavior for the definition (ignoring transient glitches).
• “Never decreases” refers to the final settled output after each code step.

Concept / Approach:
A DAC is monotonic if each increment in code results in an output that is greater than or equal to the previous output. This property ensures no “code reversals,” where a higher code produces a lower output, which can destabilize control loops and degrade audio or instrumentation quality. Monotonicity is closely related to differential nonlinearity (DNL); a DAC with DNL greater than −1 LSB is guaranteed monotonic.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets often state “monotonic to n bits,” indicating guaranteed adherence to this property over the specified code range.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing monotonicity with linearity; a DAC can be monotonic yet have significant INL.

Final Answer:
monotonic