Doherty Power Amplifier Based on the Fundamental Current Ratio for Asymmetric cells

This paper presents a Doherty power amplifier (DPA) based on asymmetric cells using an even input power drive and an appropriate peak fundamental current ratio (FCR) between the peaking amplifier and the carrier amplifier. Using an appropriate output combiner and an even input power drive for the DPA, not only better load modulation but also enhanced power gain can be achieved. After providing an analysis for the fundamental currents, a design guide for the proposed DPA using the peak FCR is presented. For verification, conventional and proposed DPAs were designed using GaN-HEMTs for the 2.14-GHz band. Using a downlink long-term evolution signal having a peak-to-average power ratio of 6.5 dB, comparably better performances were achieved than the conventional DPAs, such as a high power-added efficiency of 55.7% and a power gain of as high as 16.6 dB, at an average output power level of 36.9 dBm.