This article presents selected aspects relating to digital signal processing in digital control circuits in power electronics. The following typical problems are discussed in this paper: signal sampling rate (phenomena of aliasing, synchronization) coherent sampling, jitter of sampling pulse, sequential vs. simultaneous sampling in a multichannel system, signal resolution (signal-to-noise ratio, noise shaping circuit, changing of sampling speed) interpolation and decimation, and conversion of analog circuits to digital form. In this paper a new formula for calculation of the resultant signal-to-noise ratio for three stages digital control circuit is presented. Consideration of these sources of error and their subsequent correction allows for a greater signal-to-noise ratio and minimization of distortion components, which in turn results in improved parameters of output/input currents and voltages, which can further affect the quality of energy processing in power electronic circuits.