A 31–41 GHz SiGe Power Amplifier with Sandwiched-Coupler-Balun and Folded-T-Line Power Combiner Achieving 23.5-dBm/22.2-dBm Psat/OP1dB and Supporting 64-QAM Modulation

This paper presents a two-way parallel combined 31–41 GHz power amplifier (PA) with high-power and high-efficiency in 130nm SiGe BiCMOS process. Sandwiched-coupler-balun and folded transmission line (T-line) are utilized in the two-way power combining network to realize broadband matching and reduce insertion loss. Additionally, parallel peaking inductors are utilized to improve the stability and efficiency of the cascode amplifiers. The proposed PA achieves a peak S21 of 30.5 dB at 34.8 GHz and small-signal 3-dB bandwidth of 10 GHz (31–41 GHz). The PA also achieves 23.5 dBm Psat with 33.9% peak PAE and 22.2 dBm OP1dB at 35 GHz. The Psat and peak PAE of the PA remains 22.7-23.8 dBm and 24.5-33.9% across 31–39 GHz respectively. In modulation test, the measured EVM/ACLR of the PA is below - 25.4 dB/-25.3 dBc with 250 MSym/s 64-QAM signal at 35 GHz.