A Modified Doherty Power Amplifier With Extended Bandwidth and Reconfigurable Efficiency

This paper derives the theory and presents measurements of a new power amplifier based on the Doherty power amplifier topology. It is theoretically shown that the proposed amplifier can simultaneously provide high efficiency at both full output power and at output power back-off, over a much improved bandwidth compared to the conventional Doherty power amplifier. It is also shown that the proposed amplifier allows reconfiguration of the efficiency in power back-off without the need of tunable elements. A demonstrator circuit with individually controlled main and auxiliary amplifier input signals is designed to validate the theoretical findings. Measurements show state-of-the-art efficiency bandwidth with more than 49% drain efficiency at both full output power (42 dBm) and at 6 dB output power back-off (36 dBm) over a 1.5-2.4 GHz frequency range. The measurements also demonstrate that the efficiency in back-off can be conveniently reconfigured. The measurements thereby validate the presented theory and demonstrate the potential of the proposed amplifier for use in future wireless transmitter applications.