This paper presents the mechatronic analysis and performance estimation of a pulse-width modulated permanent magnet synchronous motor (PMSM), which is part of a direct-drive rotational servo system. Physical modeling together with dynamic error budgeting are applied to identify the minimal required switching frequency that maximizes the energy efficiency of the system while maintaining the required precision. The analysis is carried out for a wide velocity range and considers various friction phenomena. The disturbances induced by the switched amplifier are also considered and compared to a linear amplifier. The accuracy of the derived model and analysis is experimentally verified over the entire velocity range as well as for the considered range of switching frequencies.