Study On The Left-Handed Transmission Line Based Filters

In recent years,due to the unique electromagnetism characteristic,the left-handed(LH)metamaterials(MTMs)have become a hot research topic in electromagnetic field.However,the study on the left-handed transmission line(LH TL)is still at the stage of exploration,and there are also many theory and practice works need to be done.Based on the rigorous analysis of the guiding characteristics of the TL in Complementary Metal-Oxide-Semiconductor(CMOS)process,some filter prototypes are proposed in this dissertation,including bandpass filter(BPF)based on the dual-behavior resonator,right-handed transmission line(RH TL)based combline filter,LH TL based dual-band BPF?combline filter and dual-mode filter.Firstly,this dissertation embarks from the extracted guiding characteristics of the conventional microstrip TL and the complementary conducting strip transmission line(CCS TL),demonstrated the feasibility of the implementing of terahertz filters in CMOS process.Meanwhile,a BPF based on the dual-behavior resonator and a traditional combline filter are designed to verify this.Secondly,a novel LH TL based dual-band resonator and the dual-band BPF based on the novel resonator are proposed in this dissertation.A novel dual-band resonator can be achieved by combining an open stub RH TL and an open-circuited LH TL in parallel.The RH TL introduces a transmission zero at its quarter-wavelength frequency.When the electrical length of LH TL is less than a quarter-wavelength,the input susceptance of the open stub LH TL is negative,which can make a parallel resonance with the RH TL.In addition,the LH TL produces a transmission zero at its quarter-wavelength frequency and acts as a parallel resonator affording a transmission pole when the phase-lead approaches to ?.Moreover,the highpass guiding characteristics of the LH TL naturally realize wide stopband at lower frequency.The large slow wave factor of LH TL makes the proposed resonator achieving a greatly circuit miniaturization.Thirdly,a novel LH TL based combline filter is proposed in this dissertation.Compared with the conventional RH TL based combline resonators,the LH TL combline resonators are open stub at one end and with a capacitor loaded between the other end and ground.A detailed description of the synthesis procedure for a two-order LH TL combline BPF is presented by the analysis of the capacitor-loaded LH TL resonator,the coupling of the LH TL resonators and the input/output tapping of the combline filter.Furthermore,different from the RH TL types,the LH TL combline BPF has a spurious band in low frequency region near the onset frequency of LH TL.Finally,a novel negative-order dual-mode BPF based on LH TL ring resonator is presented in this paper.The negative-order resonance frequency of the LH TL ring resonator can be calculated from the frequency dependent slow-wave factor extracted from the scattering parameter analysis,the period of the unit cell of the LH TL and the number of the unit cell of the resonator.The degenerate modes of LH TL ring resonator can be excited by adjusting the size of the perturbation capacitor,the length of the perturbation inductor and by inserting a segment of RH TL.Both current distribution of single mode and dual-mode LH TL ring resonator are exhibited.In order to obtain a larger coupling coefficient for the moderate bandwidth filter design,the three type perturbation methodologies could organic unifies in together.