An enhanced switching policy for buck-derived multi-level switching power amplifiers

Abstract

This work proposes a switching policy for multi-level fullbridge switching power converters and analyses their performance by driving them with a multi-level PWM modulation, targeting highefficiency power amplifiers. Unlike conventional policies, which generate the output voltage levels only from the values of the supply voltages, this enhanced policy also uses the values of the voltage difference between supply voltages to generate additional output voltage levels, therefore maximising the number of output voltage levels for a given set of supply voltages and connection switches. Simulation results show that, when tracking a band-limited signal, the proposed switching policy can reduce the power of the high-frequency spectral content from 21% to 11% by upgrading a 5-level amplifier to a 7-level amplifier without adding supply voltages or connection switches.