Wideband SPDT and SP4T RF Switches Using Phase-Change Material in a SiGe BiCMOS Process

This paper presents, for the first time, high performance wideband RF switches, single pole double throw (SPDT) and single pole four throw (SP4T), using phase change material (PCM) monolithically integrated into a SiGe BiCMOS process. The insertion loss (IL) for the SPDT is less than 0.42 dB and 0.6 dB for frequencies up to 20 GHz and 60 GHz, respectively. The SP4T IL is 0.44 dB, and 0.9 dB for the aforementioned frequencies. Both of the switches achieved very good return loss and isolation. The switches are designed using a series only architecture to reduce the number of PCM devices needed to toggle while achieving more than 35 dB and 25 dB of isolation up to 20 GHz and 60 GHz respectively. A million toggling cycles for a single pole single throw (SPST) switch shows a competitive endurance in terms of insertion loss and isolation.