A Linear and Efficient Power Amplifier Supporting Wideband 64-QAM for 5G Applications from 26 to 30 GHz in SiGe:C BiCMOS

Abstract

This paper presents a compact transformer-based linear and efficient power amplifier (PA) in 0.13-μm SiGe:C BiCMOS for 5G applications. To reduce the form factor, an ultra-compact neutralized cascode PA core is proposed, which achieves a state-of-the-art power density. To obtain a gain flatness at 5G NR band n257 (26.50-29.50GHz), transformer-based input and output matching networks are designed. The PA demonstrates a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{21}$</tex> 3-dB bandwidth <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(BW_{-3\text{dB}})$</tex> of 10.5GHz from 23.5 to 34GHz. At 28GHz/29GHz, the saturated output power ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text{sat}}$</tex> ) are 22.7/22.4dBm with power-added efficiency (PAE) of 38.1/39.8%. The PA also supports 64- and 256-QAM modulated signal tests without digital pre-distortion (DPD). Over 26-30GHz, for 4.8Gb/s 64-QAM signals with peak-to-average power ratio (PAPR) 8.3dB at −25dB EVM, this PA continuously achieves >16dBm average power ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text{avg}}$</tex> ) with >11% PAE.