A 24–30-GHz GaN-on-SiC T/R Front-End Module With 37.5-dBm Output Power and 32% Peak PAE Based on Second-Harmonic Control Technique

This article presents a 24–30-GHz wideband transmit–receive (T/R) front-end module (FEM) for 5G millimeter-wave (mm-Wave) applications in the 150-nm GaN-on-SiC HEMT process. The power amplifier in the transmitting chain is constructed of two fully symmetrical push–pull amplifiers that are designed using transformer-based baluns. To improve efficiency, the harmonic control technique is used in the output impedance matching network, where the second-harmonic impedance can be optimized without affecting the fundamental response. A high-order stacked-transistor single-pole double-throw (SPDT) switch is designed with a low insertion loss of 0.75dB and a high input 1-dB compression point (IP${}_{\mathrm {1dB}}$) of over 44dBm, ensuring almost no gain compression in transmitting mode. The low-noise amplifier (LNA) in the receiving chain is designed into a three-stage topology, achieving a flat gain and low-noise figure (NF) within the operating bandwidth. In measurements, the proposed FEM operating across 24–30 GHz demonstrates a maximum saturated power ($P_{\mathrm {sat}}$) of 37.5dBm and peak power-added efficiency (PAE) of 32% in the transmitting mode. An error vector magnitude (EVM) of 5.75% and an average output power of 25.7 dBm with a 64-quadrature amplitude modulation (QAM) 5G FR2 modulated signal of 100-MHz bandwidth at 27 GHz are realized. In the receiving mode, the FEM demonstrates a NF of less than 3.1 dB, a flat small-signal gain of 20–21.3 dB, and an output 1-dB compression point (OP${}_{\mathrm {1dB}}$) of 20.4 dBm.