A low-loss single-pole-double-throw (SPDT) switch circuit using lateral RF MEMS switches has been developed on glass to operate from DC to 20 GHz. High compactness and low loss can be obtained by use of the lateral switches and coplanar waveguide (CPW) configuration. The circuit provides > 24-dB isolation and < 0.9-dB insertion loss up to 20 GHz. The pull-in voltage of the switch is only 12.4 V, with a switching-on time of 35 μs and a switching-off time of 36 μs. A single-mask silicon-on-glass (SiOG) fabrication process has been developed to fabricate the SPDT switch circuit on glass, which has the advantages of low loss and high yield. The whole circuit has a size of 1.64 mm × 1.3 mm. ©2007 IEEE.