Design of a Wideband Doherty Power Amplifier with High Efficiency for 5G Application

Abbas Nasri,Motahhareh Estebsari,Anna Piacibello,Marco Pirola,Chiara Ramella,Siroos Toofan,Vittorio Camarchia

doi:10.3390/electronics10080873

Abbas Nasri, Motahhareh Estebsari + Show 5 more

Open Access

https://doi.org/10.3390/electronics10080873

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Abstract

This paper discusses the design of a wideband class AB-C Doherty power amplifier suitable for 5G applications. Theoretical analysis of the output matching network is presented, focusing on the impact of the non-ideally infinite output impedance of the auxiliary amplifier in back off, due to the device’s parasitic elements. By properly accounting for this effect, the designed output matching network was able to follow the desired impedance trajectories across the 2.8 GHz to 3.6 GHz range (fractional bandwidth = 25%), with a good trade-off between efficiency and bandwidth. The Doherty power amplifier was designed with two 10 W packaged GaN HEMTs. The measurement results showed that it provided 43 dBm to 44.2 dBm saturated output power and 8 dB to 13.5 dB linear power gain over the entire band. The achieved drain efficiency was between 62% and 76.5% at saturation and between 44% and 56% at 6 dB of output power back-off.

Highlights

With the continuous evolution of wireless systems towards higher data rates and lower power consumption, the need for high-performance transceivers has increased [1,2,3]
While the wider RF bandwidths achievable in the FR2 range allow relaxing the complexity of the adopted modulation schemes, PAs working in the FR1 range need to operate as efficiently as possible with modulations as complex as 4096-Quadrature Amplitude Modulation (QAM)
Wideband Computer-Aided Design (CAD) optimization was performed on the designed Output Matching Networks (OMNs) to fine-tune their behavior across the bandwidth

Summary

Introduction

With the continuous evolution of wireless systems towards higher data rates and lower power consumption, the need for high-performance transceivers has increased [1,2,3]. While the wider RF bandwidths achievable in the FR2 range allow relaxing the complexity of the adopted modulation schemes, PAs working in the FR1 range need to operate as efficiently as possible with modulations as complex as 4096-Quadrature Amplitude Modulation (QAM) These kinds of modulations feature a time-varying envelope with a very high peak-to-average power ratio (PAPR); to cope with such signals, power amplifiers are required to have high efficiency, at saturation, and at lower output power levels [10,11,12,13].

Doherty Power Amplifier Design

Output Matching Network Design

Measurements Results

Conclusions