A 24.25-27.5 GHz Front-End Module with Transformer-Based T/R Switch for 5-G communications

An innovative 24.25-27.5 GHz front-end module (FEM) with an ultra-compact transformer-based transmit/ receive switch (TRSW) is introduced in this paper. The TRSW which consists of a four-inductor coupled resonator (three-winding transformer and a source degeneration inductor), a shunt transistor switch and a two-bit capacitor bank, functions as TRSW, balun and matching networks within only an inductor footprint. It is co-designed with the low noise amplifier (LNA) and power amplifier (PA) to achieve minimum noise figure (NF) and maximum output power and linearity. To prove the concept, the FEM is implemented in a 65-nm CMOS process. The measurement results demonstrate that the FEM achieves 25.5 dB small signal gain with a 5.9 dB minimum NF in RX mode, while the FEM achieves 14.4 dBm OP1dB and 16 dBm Psat in TX mode, demonstrating the best OP1dB when compared to state-of-the-art 28-GHz FEMs.