SPST and SPDT 60 GHz Travelling-Wave Switches in 22 nm FD-SOI

This work presents 60 GHz travelling-wave Single-Pole Single-Throw and (SPST) and Double-Throw (SPDT) switch designs implemented in the 22 nm fully-depleted SOI technology from GlobalFoundries. The full SPDT is composed of a Quarter-Wavelength Impedance Transformer (QWIT) and two SPST cores also fabricated as a standalone devices. The paper details a comprehensive design procedure of the SPST branches and presents the on-wafer measurement data. The losses associated to the QWIT and SPST cores are analyzed in detail and correlated to the performance of the full SPDT design based upon those elements. At 60 GHz, the full SPDT module presents an isolation of 32 dB and an insertion loss of 1.6 dB. Through our dedicated measurement test structures, we identify the various contributing factors to that overall loss, loss induced by the QWIT, by both the transmitting and isolating SPST cores, and by the spiral inductors and FD-SOI devices they are based on.