Analysis and Design of Transformer-Based mm-Wave Transmit/Receive Switches

Transformer-based shunt single pole, double-throw (SPDT) switches are analyzed, and design equations are provided. A mm-wave transformer-based SPDT shunt switch prototype was designed and fabricated in 90 nm digital CMOS process. It has a minimum insertion loss of 3.4 dB at 50 GHz from the single pole to the ON-thru port and a leakage of 19 dB from the single pole to the OFF-thru port. The isolation is 13.7 dB between the two thru ports. Large signal measurements verify that the switch is capable of handling +14 dBm of input power at its 1 dB compression point. The fabricated SPDT switch has a minute active area size of 60 μm×60 μm.