The output of a DAC can only assume discrete values. The relationship between the input binary number and the analog output of a perfect DAC is shown in figure 8.3.
Figure 8.3: Output signals from DACs showing a) the ideal
result, and b) a differential nonlinearity or c) non-monotonic behavior,
both caused by imperfectly matched resistors.
Common DAC limitations are an anomalous step size between adjacent binary numbers, non-monotonic behaviour, or a zero output.