| This thesis presents measurement and electromagnetic simulation-based modeling of (i) high-frequency flip-chip interconnects and (ii) micro-electro-mechanical-system (MEMS) capacitors and switches. In the first part, the objective is to characterize flip-chip interconnects with and without underfill based on experimental measurement and electromagnetic (EM) simulation, and to investigate the effect of flip-chip joints on RF performances of coplanar waveguide (CPW) circuits. In the second part, the objective is to design and characterize RF MEMS tunable capacitors and switches, and thereby develop design guidelines and methodology for RF MEMS devices.;An RF model of CPW flip-chip joints, based on EM simulation and RF measurement, has been developed for frequencies up to 40 GHz. For the specific design considered, the inductance due to the flip-chip joint is about 0.012 nH. Also, effects of the underfill epoxy on flip-chip assemblies have been studied. Additional loss due to underfill is 0.22 dB/mm and additional transmission phase delay is 13 deg/mm at 40 GHz. This additional phase delay can be compensated by redesigning dimensions of transmission lines in the RF circuit.;CPW compatible high-Q series- and shunt-mounted variable capacitors using MEMS (with thermal actuation) have been designed, characterized and measured. Lumped-element models have been developed for these MEMS capacitors. Effects of actuators and thickness of the gold layer on the MEMS plate have been analyzed to improve RF performances of these MEMS variable capacitors. Design guidelines for RF MEMS variable capacitors have been developed based on characterizations of these capacitors. For the shunt-mounted capacitor design, the measured value of the shunt resistance (R), which is series with the tunable capacitance, is 0.15 O, the measured capacitance is 0.272 pF, the Q-factor is approximately 390 at 10 GHz, the self-resonance frequency is beyond 40 GHz, and the simulated maximum to minimum capacitance ratio is about 5:1. For the series-mounted capacitor design, the measured R is 4.2 O, the measured capacitance is 0.331 pF with 0 volt bias voltage, the Q-factor is approximately 110 at 1 GHz, the measured tuning ratio is about 2.66:1 with the actuation voltage varied from 0 to 2.5 volts, and the self-resonance frequency is 14 GHz when bias voltage is 2.5 volts. For RF MEMS multiway switches, a design method has been developed. Using this method, 2-port MEMS switches have been designed and optimized. The insertion loss is approximately 0.1 dB and the isolation is 22 dB at 14 GHz. Initial designs of 3-port and 4-port MEMS switches have been carried out and characterized. |
