A novel CPW based phase shifter that relies on automatic collapse of capacitive switches is designed, fabricated and tested. The novel design of the phase shifter is due to a novel CPW topology and automatic collapse mechanical design that is designed to operate at several and gradual collapse voltages. The novelty of the CPW has been achieved through the corrugated grounds to create a slow wave transmission line. The resulted compact CPW will have an effective electrical length that is physically equivalent to a relatively longer conventional CPW. The automatic collapse of the designed capacitive switches comes through deferent lengths of the beams that are carrying those capacitive switches. The worst measured insertion loss and return loss are 1.7 dB and 13 dB, respectively, at 30 GHz with a phase shift of almost 106 degrees. The phase shifter is built on alumina substrate of gold material using UWMEMS process.