Planar ring structures for innovative design of compact microwave filters

171 p.Microwave filters with high performance and compact size are always in high demand. The objective of this PhD thesis is to explore planar ring structures for compact microwave filter designs. We first explore dual-mode dual- and triple-band bandpass filters using single ring resonators, which significantly reduce the overall physical size. Two methods are proposed to design dual-mode dual-band bandpass filters using single ring resonators. The first method is to synchronously excite the first- and third-order degenerate resonant modes of a ring resonator. Using this method, a compact dual-bandpass filter with center frequencies at 2.4 and 5.8 GHz is designed and fabricated. The second method is to excite the first two pairs of degenerate resonant modes of a ring resonator. Several prototype filters are fabricated and measured to prove our design theory. In particular, a dual-bandpass filter using a slot ring resonator is design to operate at 2.4 and 5.2 GHz. The concepts are extended to design a dual-mode triple-band bandpass filter based on the first three pairs of degenerate modes of a ring resonator. Two triple-band bandpass filters are designed with this purpose. Later, a modified ring structure, known as a hairpin unit, is successfully implemented for wide-stopband lowpass filter design. In addition, a synthesis method is developed to design lowpass filters with Chebyshev-function frequency responses using stepped-impedance hairpin units. Finally, we apply our knowledge about ring resonators for millimeter-wave bandpass filter design in 0.18 um CMOS technology. The fabricated filter achieves an ultra-compact size of 0.092 x 0.56 mm2. The measured results verify the proposed design topologies.Doctor of Philosophy (EEE