A Review of 5G Power Amplifier Design at cm‐Wave and mm‐Wave Frequencies

The 5G wireless revolution presents some dramatic challenges to the design of handsets and communication infrastructures, as 5G targets higher than 10 Gbps download speed using millimeter‐wave (mm‐Wave) spectrum with multiple‐input multiple‐output (MIMO) antennas, connecting densely deployed wireless devices for Internet‐of‐Everything (IoE), and very small latency time for ultrareliable machine type communication, etc. The broadband modulation bandwidth for 5G RF transmitters (i.e., maximum possibly even above 1 GHz) demands high‐power efficiency and stringent linearity from its power amplifier (PA). Additionally, the phased‐array MIMO antennas with numerous RF front‐ends (RFFEs) will require unprecedented high integration level with low cost, making the design of 5G PA one of the most challenging tasks. As the centimeter‐wave (cm‐Wave) 5G systems will probably be deployed on the market earlier than their mm‐Wave counterparts, we will review in this paper the latest development on 15 GHz and 28 GHz 5G cm‐Wave PAs extensively, while also covering some key mm‐Wave PAs in the literature. Our review will focus on the available options of device technologies, novel circuit and system architectures, and efficiency enhancement techniques at power back‐off for 5G PA design.