A Review of Technologies and Design Techniques of Millimeter-Wave Power Amplifiers

Abstract

This paper reviews the state-of-the-art of millimeterwave power amplifiers, focussing on broadband design techniques. An overview of the main solid-state technologies is provided, including Si, GaAs, GaN and other III-V materials, and both field-effect and bipolar transistors. The most popular broadband design techniques are introduced, before critically comparing through the most relevant design examples found in the scientific literature. Given the wide breadth of applications that are foreseen to exploit the millimeter-wave (mm-wave) spectrum, this contribution will represent a valuable guide for designers who need a single reference before adventuring in the challenging task of mm-wave power amplifier design. Index Terms-Broadband, millimeter wave, power amplifiers. I. INTRODUCTION T HE millimeter-wave (mm-wave) spectrum is attracting a great interest for applications such as 5G and future satellite communications that go well beyond the traditional niche of military and scientific use in terms of investments and potential revenues. The most attractive feature of mm-waves compared to the RF and microwave band is the huge spectrum availability that gives a great advantage in terms of capacity for telecommunication systems. Other advantages of mm-wave systems are the compact size of circuits, especially antennas, and the intrinsic easiness of frequency reuse thanks to the high free-space attenuations. There are also some advantages that are band-specific; for example, the very high attenuation in the 60 GHz band due to oxygen absorption that enables intrinsically secure communications. On the other hand, the very high frequency of operation poses significant challenges to system and circuit design. Similarly to what happens at lower frequency, one of the most critical circuit components is the power amplifier (PA). Its

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