Current contours based IMN design methodology for broadband GaN Doherty power amplifiers

Abstract

This paper proposes a design methodology based off the novel concept of current contours to insure proper current profiles for the main and peaking transistors needed to satisfy the load modulation conditions in a Doherty power amplifier over a wide frequency range. Utilizing this technique allows the construction of input matching networks that maximize the efficiency enhancement and linearity of the DPA. As a proof-of-concept, a 12 W DPA was designed. From 2.7 GHz to 4.7 GHz, continuous wave measurements have shown efficiency levels of greater than 37 % at 6 dB output power back-off and peak power. A gain of at least 8 db was shown with output power ranging from 40.7 dBm ±1 dB. Under an 80 MHz carrier aggregated signal, modulated signal results showed good linearizability with an ACLR of −48 dBc/Hz after digital pre-distortion.