| High permittivity dielectric materials play key roles in the miniaturization of microwave filters and multiplexer networks for wireless communications. The first part of this dissertation is devoted to advance the state of the art of microwave CAD of filters homogeneously or inhomogeneously-filled dielectric resonators.; Rigorous numerical methods are employed to analyze the design parameters of the filters. Improved small aperture approximation together with experimental technique show tremendous improvement on design efficiency and quality for the conventional dual-mode dielectric resonator filters. To improve the spurious performance, a new filter, mixed mode dielectric resonator filter, is proposed. A new configuration of air-filled or dielectric-filled dual-mode filter is presented. With a section of corner-cut waveguide at the center of the cavity, all the tuning and coupling screws are eliminated. A novel design technique is developed for this filter. Curve-fitting and experimental techniques are applied to improve the efficiency on filters and multiplexers designs.; The second part of this dissertation proposes a compact transistor model to include the dynamic thermal effects of semiconductor devices. The temperature increment is fed back to change the electrical parameters of the device model. The model is successfully implemented in SPICE3 and verified by experimental data. The application to simulate the collector current of a HBT is also presented. |
