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

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
$S_{21}$
3-dB bandwidth
$(BW_{-3\text{dB}})$
of 10.5GHz from 23.5 to 34GHz. At 28GHz/29GHz, the saturated output power (
$P_{\text{sat}}$
) 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 (
$P_{\text{avg}}$
) with >11% PAE.