Multi-Cell Switch-Mode Power Amplifier with Closed-Loop Hybrid Output Voltage Filter

Inhalt:
In this paper a promising novel output voltage filtering concept for multi-cell switch-mode power amplifiers is analyzed. The proposed hybrid filtering concept is based on a passive LC filter enhanced by a linear-mode correction stage of small rated power. Using this principle, also "sub-harmonic" (i.e. low-frequency) switching noise distortions (typically appearing in real interleaved multi-cell switching amplifiers) can be effectively suppressed which is not possible using conventional LC filters. Combining the new hybrid filtering approach with a switch-mode power amplifier formed by an arrangement of low-voltage MOSFET switching cells finally results in a power source of high output voltage precision at high efficiency rates.