Ka Band FEM Design Comparison with 45nm RFSOI CMOS and High Performance SiGe BiCMOS

Abstract

45nm RFSOI NFET has similar F T /F max as high performance 130nm SiGe NPN and they are both potentially suitable for Ka Band FEM applications. In this paper, we evaluated the Ka band LNA, SPDT, and PA based on both processes. A 28GHz LNA designed with 45nm RFSOI does present a lower noise figure advantage of about 1.4dB compared to ~2dB noise figure of a LNA designed with SiGe NPN. For SPDT, due to low parasitic capacitance in SOI process, based on traditional stack solution, RFSOI process shows about 1dB IL advantage compared with SPDT designed with a bulk SiGe BiCMOS process. While in the high performance SiGe process, a transmission line based SPDT or other advanced topology can get better performance than traditional stack solution with larger area. For PA's, the SiGe device has higher breakdown voltage than a single FET in 45nm CMOS process, so from power density point of view, SiGe has higher power density. But the SOI process provides the stack solution, so the RFSOI overall output power of a single PA without power combination is similar to one designed with the SiGe NPN.