Active Hybrid Filter Applied with a Multi-Cell Switch-Mode Power Amplifier

This paper discusses an active filtering method applied on a multi-cell switch-mode power amplifier. One main purpose of this system is to build high quality power sources up to the kW-region. The system is formed by a switch-mode and a linear amplifier. The power allocation of the two parts is approximately 10:1 depending on the operation mode of the system. The switch-mode power amplifier is realized by a multicell amplifier with a passive LC-filter, which is actively damped by feeding back the capacitor current. The workload of the linear amplifier is influenced by the factors input frequency and load current which are examined in this paper. The benefit of the presented system is the low rated voltage and current of the linear stage. The performance of the whole system's output voltage is demonstrated by measurements in the time domain and by high resolution spectra.