Spectral estimation of piece-constant waveforms generated by digital-to-analog converters

DACs are frequently utilized to generate non-standard waveforms. In particular any DACs approximate the desired waveform with a piece-constant one, produced by stepping up or down the output voltage of some amount at regular time intervals. The effect of the voltage steps characterizing piececonstant waveforms have been barely investigated in the past years. The paper presents a descriptive model for DACs that takes into account the piece-constant nature of the output waveform as well as non-idealities, such as time-base instability and non-linearity errors. The model describes well the behaviour of real DACs and permits to estimate the spectral features of the generated waveform, avoiding some pitfalls the simulation can be responsible for.