Low-loss cascadable MEMS distributed X-band phase shifters

A wideband distributed coplanar-waveguide (CPW) phase shifter has been deve loped for X-band operation, The design is based on the distributed MEMS tra nsmission line (DMTL) loaded with high capacitance-ratio varactors, The var actors are fabricated using a series combination of MEMS bridges and fixed- value MIM capacitors. A high-capacitance ratio varactor (1.5-2.5) results i n a large loading on the CPW line and therefore a large phase shift, A dist ributed phase shifter was fabricated on a 500 mu m quartz substrate, and ac hieved a true-time delay operation from 1 to 10 GHz with a reflection coeff icient less than -15 dB, and 180 degrees/dB of insertion loss at 8-10 GHz, It is possible with this design to cascade the DMTL to result in 2- and 3-b it phase shifters with excellent wideband performance at X-band frequencies .