Optimization of distributed MEMS transmission-line phase shifters-U-band and W-band designs

The design and optimization of distributed micromechanical system (MEMS) transmission-line phase shifters at both U- and W-band is presented in this paper. The phase shifters are fabricated on 500 μm quartz with a center conductor thickness of 8000 Å of gold. The U-band design results in 70°/dB at 40 GHz and 90°/dB at 60 GHz with a 17% change in the MEMS bridge capacitance. The W-band design results in 70°/dB from 75 to 110 GHz with a 15% change in the MEMS bridge capacitance. The W-band phase-shifter performance is limited by the series resistance of the MEMS bridge, which is estimated to be 0.15 Ω. Calculations demonstrate that the performance of the distributed MEMS phase shifter can be greatly increased if the change in the MEMS bridge capacitance can be increased to 30% or 50%. To our knowledge, these results present the best published performance at 60 and 75-110 GHz of any nonwaveguide-based phase shifter.