A Dual-Band Reconfigurable Filtering Power Amplifier for 5G mmWave Applications

This article presents a frequency reconfigurable power amplifier (PA) for fifth-generation (5G) millimeter-wave dual-side local oscillator (LO) injection systems, which effectively reduces the LO design complexity. A tricoil transformer is proposed to design a high$Q$broadband output matching network (OMN), thus enhancing power-efficiency at high-frequency band. Besides, two distinct reconfigurable resonator topologies are proposed for the design of both the input and interstage matching networks. These resonators effectively realize filtering functionality by utilizing the switch-off capacitance in conjunction with inductive resonance, while maintaining low-circuit losses. Importantly, this design methodology inherently embeds filtering capabilities within the matching network without introducing additional area overhead. The proposed PA is implemented in 28-nm bulk CMOS and realizes 18.4–20.2 dBm$P_{\text {sat}}$, 13.7–19 dBm OP1dBand 24.5%–34.7% PAE over n257–n261 bands. The PA exhibits maximum image/LO rejection (LOR) of 38.5/28.5 dBc. For 5G new radio (NR) frequency range 2 (FR2) 200 MHz 64-QAM signals (9.7 dB PAPR), the PA achieves average$P_{\text {out}}$/PAE of >7.3 dBm and >5.2% with −25 dB EVMrmsover n257–n261. The PA occupies a core area of only 0.109 mm2, making it suitable for cost-effective, high-yield 5G user equipment (UE) and large-scale phased-array applications.