From the equation for the ideal DAC output, it can be concluded that the DAC transfer function is linear. That is, the relationship between the input codes and output voltage or current is linear. Said differently, a DAC’s input codes and its analog output values have a 1-to-1 correspondence related by a straight line. The two traces shown here depict DAC transfer functions, that is, the relationship between output values and input codes. The horizontal axis indicates DAC input codes, x, from 0 to 2 to the D minus 1. The vertical axis represents the DAC output value in LSB units. A perfect DAC exhibits a perfectly straight line for its transfer function, as demonstrated by the blue trace. A real DAC, however, has errors that can result in a warped transfer function, as shown by the red trace. A warped DAC transfer function causes harmonic distortion in its output spectrum.