A new single-pole-double-throw (SPDT) switch circuit using high-aspect-ratio lateral RF microelectromechanics system (MEMS) switches has been designed to operate from DC to 20 GHz. By using lateral switches and coplanar waveguide configuration, compactness and low-loss can be obtained. The circuit provides greater than 22 dB isolation and less than 0.9 dB insertion loss up to 20 GHz. A low-cost high-yield silicon-on-glass (SOG) fabrication process has been developed to fabricate this SPDT switch circuit. The size of the whole circuit is only 1.64 mm × 1.3 mm in area. © 2005 IEEE.