In a DAC, which statement correctly defines DNL and INL?

• A. DNL is the deviation of the actual step size between adjacent codes from 1 LSB; INL is the deviation of the transfer function from the ideal straight line.
• B. DNL is the total offset error; INL is the gain error.
• C. DNL affects monotonicity only; INL does not.
• D. DNL and INL are both the same as integral nonlinearity.

Answer: (A)

Understanding what DNL and INL measure in a DAC helps you predict how the converter will distort a stepped output. DNL, or differential nonlinearity, looks at the size of each step between consecutive output codes. If a step isn’t exactly one least-significant-bit wide, that difference from 1 LSB is the DNL. INL, or integral nonlinearity, examines the overall transfer curve: how far the actual output for a given input deviates from the ideal straight-line transfer. It’s the cumulative effect of all the step-size errors across the entire code range.

So, the statement that correctly defines both is that DNL is the deviation of the actual step size between adjacent codes from 1 LSB, and INL is the deviation of the transfer function from the ideal straight line.

The other descriptions mix up what each term measures or describe them incorrectly. For example, offset or gain errors aren’t the precise definitions of DNL or INL, and large DNL can affect monotonicity (not just cause monotonicity to fail in a limited way), while saying both are the same as integral nonlinearity mislabels the differential nature of DNL.