A single-pole double-throw (SPDT) circuit using deep etching lateral metal-contact switches

In this paper, a single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches fabricated on silicon-on-insulator (SOI) wafer is demonstrated to operate from DC to 6 GHz. The size of the fabricated SPDT switch is about 1.2 mm×1.5 mm. The lateral metal-contact micromachined switches are farmed on the quasi-finite ground coplanar waveguide (FGCPW) transmission lines and actuated by electrostatic force. The fabricated single-pole single-throw (SPST) lateral micromachined switch has an insertion loss of 0.2 dB and a return loss of 24 dB at 15 GHz. The isolation is 23 dB at 15 GHz. As for the fabricated SPDT switch, the measured insertion loss is below 0.75 dB and the return loss is higher than 19 dB at 5 GHz. The isolation at 5 GHz is above 33 dB. The threshold voltage of these switches is 22.5 volts, and these SOI switches are fabricated using deep reactive ion etching (DRIE) and shadow mask technology.