Abstract:

The design and fabrication of low loss distributed MEMS phase shifter are presented. The principle for this phase shifter is that the phase velocity can be varied by mean of snapping down the membrane of MEMS loading capacitors of the transmission line. Its MEMS capacitors and control voltage are discussed in detail.Several different membranes are used as the membranes and Al_0.96Si_0.04 alloy shows the best performance with pulling down voltage of the MEMS phase shifter no more than 40 V. There is a phase shift when the control voltage is only 10 V. With the phase shifter fabricated on the high resistivity silicon (ρ > 4000 Ω·cm), the insert loss is very low, no more than 3 dB from 1 GHz to 40 GHz. The phase shift will be more than 25° at 25 V.

Key words: MEMS phase shifter, AlSi alloy membrane, high resistivity silicon(HR Si), pull down voltage