51% efficient 50W envelope tracking broadband RF power amplifier for 6MHz bandwidth OFDM

A high efficiency envelope tracking RF power amplifier is described capable of reproducing a 6MHz bandwidth OFDM signal at 50W output power. The modulator uses the split frequency architecture with a switched mode power supply for the low frequency envelope content and a class 1.5G amplifier for the high frequency. Whereas conventional class G amplifiers switch both the positive and negative supply voltages, class 1.5G only switches the positive supply, resulting in 69% envelope modulator efficiency at 71.4W output power. When combined with a broadband class E RF amplifier, up to 51.3% efficiency could be achieved and 52.5% when envelope elimination and restoration was used. Both results are at 50W output power. Up to 8dB PAPR is reproduced under these conditions.