New Stepped Impedance Resonator Unit For Microstrip Filter Design

With the rapid development of modern communication system, the requirement of radio-frequency elements'performance is rising higher and higher. Personal portable information devices, such as cellular phone, GPS, and PDA, have been being on the way to the goal of"Always Online", resulting in the demand of higher performance radio frequency ICs and discrete elements with reduced volume and weight. Modern MMICs are available with the integration of active blocks, such as PA, LNA, and Mixer. However, integration of passive elements in MMIC is still a significant subject in both academic and industry fields.This dissertation is mainly focused on the design technology of compact, high performance microstrip filters in MMIC. Based on the advantages of harmonic suppression, compact size and wide band, SIR has been applied in microwave filters'design. Microstrip filters with significant improvement in size and performance are designed, fabricated and measured, making further use of band-stop characteristics of DGS and spurline.The main innovations in this dissertation are as follows.(1) A novel structure of asymmetric SIR is proposed in this dissertation, and its'lumped-element equivalent circuit is given simultaneously. Compact Low-pass and band-pass filters are designed, basing on SIR. Band-stop characteristics of DGS and spurlines are made use of in low-pass filter design. Mixed coupling and short lines methods are adapted in the design of band-pass filter. Measured results show that the novel SIR can reduce the size of microstrip filters, while enhance their performance.(2) A novel methodology of designing dual-mode filters (a novel pentagon patch dual-mode filter), basing on the discontinuous of SIR, is proposed in this dissertation. Through using pseudo-orthogonal input/output feed lines, novel coupling method, and asymmetry resonator structure, two orthogonal degenerate modes are got. A low insert loss, high up-band rejection and wide low-band dual-mode band-pass filter is obtained, and no extra perturbation elements are needed.