High-performance digital X -band and Ka -band distributed MEMS phase shifters.

This thesis presents the optimization, modeling and design of distributed MEMS (Micro Electro Mechanical Systems) phase shifters utilizing a high impedance transmission line (Zo > 100 O) periodically loaded by MEMS switches and either high-Q (Q > 400 at 30 GHz) capacitors for CPW designs at X-band and Ka-band, or radial stubs for a microstrip design at Ku-band. Comprehensive modeling of phase shift and losses attributable to these designs is verified by extensive fabrication and measurement of distributed structures. It is demonstrated by theory and measurements that phase shifters based on distributed MEMS t-lines have vastly superior low-loss characteristics than those based on solid-state devices such as Schottky diodes, FETs, or p-i-n diodes. The CPW, X-band, two-bit design on quartz results in a reflection coefficient better than -12.5 dB, an average insertion loss of -1.2 dB, and phase error within +/-4° at 13.6 GHz. The microstrip, Ku-band, four-bit design on silicon has a reflection coefficient better than -9.5 dB, an average insertion loss of -3.0 dB, and phase error within +/-0.5° at 16 GHz. Finally, the CPW, Ka-band, two-bit design on quartz results in a reflection coefficient better than -11.5 dB, an average insertion loss of -1.5 dB, and phase error within +/-0.5° at 37.7 GHz. As described in the thesis, the distributed design can be easily scaled to V-band and W-band frequencies for wideband low-loss performance.Ph.D.Applied SciencesElectrical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131978/2/3057959.pd