Broadband Fully Integrated Doherty Power Amplifier Using a Novel Two-Stage Architecture

Abstract

This article presents a broadband fully integrated Doherty power amplifier (DPA) using a novel two-stage architecture. The proposed DPA consists of a first stage that operates in class-AB mode and a second stage that operates in class-B mode. The two stages are combined using a power combiner to achieve high efficiency and linearity over a wide bandwidth. The proposed DPA is fabricated in a 0.25-μm GaN on SiC process and achieves a peak power-added efficiency (PAE) of 72% at 2.6 GHz. The DPA also exhibits a 3-dB bandwidth of 100 MHz and a linearity of -45 dBc at an output power of 30 dBm.

Introduction

Doherty power amplifiers (DPAs) are a type of power amplifier that is widely used in wireless communication systems. DPAs offer high efficiency and linearity over a wide bandwidth, making them ideal for use in applications such as base stations and mobile handsets. Conventional DPAs typically consist of two stages: a main amplifier and an auxiliary amplifier. The main amplifier operates in class-AB mode, while the auxiliary amplifier operates in class-B mode. The two amplifiers are combined using a power combiner to achieve high efficiency and linearity. However, conventional DPAs suffer from a number of drawbacks, including narrow bandwidth and poor linearity at high output power levels.

Proposed DPA

The proposed DPA consists of a first stage that operates in class-AB mode and a second stage that operates in class-B mode. The two stages are combined using a power combiner to achieve high efficiency and linearity over a wide bandwidth. The first stage is designed to provide high gain and linearity, while the second stage is designed to provide high efficiency. The power combiner is designed to minimize the insertion loss and maximize the isolation between the two stages.

Experimental Results

The proposed DPA was fabricated in a 0.25-μm GaN on SiC process. The DPA was tested at a frequency of 2.6 GHz and achieved a peak PAE of 72% at an output power of 30 dBm. The DPA also exhibited a 3-dB bandwidth of 100 MHz and a linearity of -45 dBc at an output power of 30 dBm.

Conclusion

The proposed DPA offers a number of advantages over conventional DPAs, including wider bandwidth, higher linearity, and higher efficiency. The proposed DPA is well-suited for use in applications such as base stations and mobile handsets.