Abstract: A microwave SOI single-pole-double-throw (SPDT) switch integrates a switch controller block, it is fabricated with 0.18 mm CMOS SOI technology, the switch controller block contains LDO (low dropout regulator) and a negative charge pump, LDO transforms the I/ O voltage to bias the switch circuits, the negative charge pump generates a negative voltage to enhance the performance of switch. The SPDT switch presents good performance, on chip test result presented that: in on state the insertion loss is less than 1.7 dB from DC to 9 GHz, its isolation in off state is better than 28.5 dB, return loss is better than -15dB, and the switching time is 1.06 ms. The total size of SPDT switch is 0.87 mm′1.08 mm.