A 28 GHz Single-Input Linear Chireix (SILC) Power Amplifier in 130 nm SiGe Technology

• Published in: IEEE journal of solid-state circuits 2020-06, Vol.55 (6), p.1482-1490
• Main Authors: Rabet, Bagher, Asbeck, Peter M.
• Format: Article
• Language: English
• Subjects: 5G mobile communication; BiCMOS integrated circuits; Distortion; Gain; Impedance; Linearity; millimeter wave (mm-wave) integrated circuits; Modulation; Power amplifiers; power amplifiers (PAs); Predistortion; Radio frequency
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2020.2967542

This article presents an integrated high-efficiency 28 GHz power amplifier (PA) employing a combination of Chireix outphasing and Doherty architectures in order to simultaneously achieve power back-off efficiency and linearity with a single RF input signal and no predistortion. The amplifier consists of a dual-input high-efficiency outphasing PA and a simple input network which serves as a power splitter and feeds the same signal to the inputs of the main and auxiliary PA cells that are biased in class-AB and class-C regions, respectively, similar to the Doherty architecture. The operation of the PA cells together with the Chireix combiner result in back-off efficiency enhancement plus systematic AM-AM and AM-PM variations which are used to correct the distortions caused by transistors, resulting in a linear response. The implemented PA demonstrates 19 dBm saturation power (Psat) with 34.4% peak power-added efficiency (PAE) and 6 dB back-off PAE of >23% at 27.5 GHz. The modulated signal performance using a 100 MHz 64QAM OFDM signal shows an average output power of 11.9 dBm with PAE >20%, EVM < 5%, and ACLR < −33 dBc without using predistortion.