High Efficiency Broadband Class E RF Power Amplifier with High Harmonics Suppression for Practical Two-Way Radio Applications

Class E power amplifiers (PA) offer high efficiency. However, with broadband class E load network, the harmonic performance degrades. In this work, this disadvantage has been overcome by implementing a new type of load circuitry. The whole PA chain consists of three stages to provide high gain and output power at the same time as required for two-way radio applications. The final PA stage uses a broadband class E load network. A novel idea of series L_xC_x with high Q roll-off harmonic filter (elliptical type) was used for this implementation. On measurement level, efficiency of 70 % and second harmonic suppression of 73 dBc across a wide bandwidth (135 to 175 MHz) is demonstrated at an output power of 6.5 W. The supply voltage was 7.2 V. According to the authors' best knowledge, the efficiency and harmonic results are the highest reported so far in the VHF frequency range with 40 MHz bandwidth.