DAC behavior — The requirement that increasing (or decreasing) the digital code by one step causes exactly one corresponding step change at the output is called what?

Introduction / Context:
When converting digital codes to analog signals, a key quality is whether the output moves predictably with each code step. Control systems and audio applications especially require that one code increment never produces a backward or erratic jump in the output.

Given Data / Assumptions:

• We are discussing a DAC operating over successive codes.
• Focus is on the relationship between adjacent codes.
• Ignore absolute gain/offset errors for this definition.

Concept / Approach:
Monotonicity means the output never decreases when the input code increases (and never increases when the code decreases). A stricter interpretation in many specs is that each single-code change results in exactly one step in the correct direction with no reversals. Missing codes or large DNL errors can break monotonicity.

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