2.1 A 28GHz/37GHz/39GHz multiband linear Doherty power amplifier for 5G massive MIMO applications

Millimeter-wave fifth-generation (5G) systems will extensively leverage massive multiple-input multiple-output (MIMO) architectures to improve their link performance. These array systems will employ many power amplifiers (PAs) operating at moderate output power (Pout), e.g., 16 PAs each with +7dBm Pout [1]. The PA energy efficiency is of paramount importance in MIMO systems for improved battery life and thermal management. Due to spectrum-efficient modulations with high peak-to-average power ratios, both PA peak efficiency and power back-off (PBO) efficiency are critical. To achieve 5G Gb/s data-rates with complex modulations, envelope tracking PAs require high-speed/high-precision supply modulators, and outphasing PAs need high-speed baseband computation, both of which pose substantial challenges in practice. Although Doherty PAs support high data-rates, existing silicon mm-wave Doherty PAs exhibit very limited PBO efficiency enhancement, mainly due to inefficient Doherty power combiners and imperfect main/auxiliary PA cooperation [2,3].

[1]  Peter M. Asbeck,et al.  Active Millimeter-Wave Phase-Shift Doherty Power Amplifier in 45-nm SOI CMOS , 2013, IEEE Journal of Solid-State Circuits.

[2]  F. M. Ghannouchi,et al.  Mitigation of Bandwidth Limitation in Wireless Doherty Amplifiers With Substantial Bandwidth Enhancement Using Digital Techniques , 2012, IEEE Transactions on Microwave Theory and Techniques.

[3]  Patrick Reynaert,et al.  Transformer-Based Doherty Power Amplifiers for mm-Wave Applications in 40-nm CMOS , 2015, IEEE Transactions on Microwave Theory and Techniques.

[4]  Sherif Shakib,et al.  20.6 A 28GHz efficient linear power amplifier for 5G phased arrays in 28nm bulk CMOS , 2016, 2016 IEEE International Solid-State Circuits Conference (ISSCC).

[5]  Shoji Otaka,et al.  A 2.4 GHz CMOS Doherty power amplifier with dynamic biasing scheme , 2012, 2012 IEEE Asian Solid State Circuits Conference (A-SSCC).

[6]  A. Grebennikov,et al.  A Dual-Band Parallel Doherty Power Amplifier for Wireless Applications , 2012, IEEE Transactions on Microwave Theory and Techniques.