Investigations On Miniaturized Microwave And Millimeter-Wave Filtering Circuits Based On Dual-Composite Right-and Left-Handed Resonators

Bandpass filter(BPF)is one of the indispensable devices in RF front-ends,which is used to select or suppress the analog signals with specific frequencies.To improve the integration level,it becomes a hot topic to merge the bandpass filter and some other devices into one block.The common filtering circuits include filtering antenna,filtering power divider,filtering switch,and etc.With the progress of wireless communication technology,the RF front-ends are developing towards the miniaturization,modularization,and high integration.In RF front-ends,the circuit size of passive devices is usually much larger than that of active devices,especially the filtering circuits.Therefore,the miniaturization of filtering circuit is very meaningful.However,the performance of filtering circuits decreases with smaller circuit size.Therefore,it is very challenging to realize the miniaturization and good filtering performance for filtering circuits,simultaneously.With the development of millimeter-wave technology,the packaging or semi-conductor processes are required for RF front-ends,which are lossy and expensive.By using these process,the conventional filtering structures are not suitable to be applied due to the large circuit size and transmission loss.To solve this issue,a novel type of dual composite right and left-handed(D-CRLH)resonators is proposed in this thesis,which is of high design flexibility and usually smaller than 1/10 guided wavelength.In addition,a synthesized method is proposed to design filtering circuits based on LC-equivalent circuit models.Significantly,the proposed methodology can be extended to printed circuit board(PCB),packaging,or semi-conductor process for many applications.Based on the proposed design method,a series of microwave and millimeter-wave filtering circuits are designed,with very compact sizes and good filtering performances.The main innovative works in this thesis can be summarized as follows:1.Investigation of the miniaturized D-CRLH resonators with high design flexibility.(a)Propose miniaturized D-CRLH resonator,whose circuit size is of only 0.05 to 0.1guided-wavelength.Different from reported(D-)CRLH structures,the proposed D-CRLH resonators has two states:can be used to design D-CRLH transmission lines,also can be used for coupled-resonator filtering circuits;(b)propose an analytical extraction method for circuit parameters,and built a mapping relation between the complex structure and simple circuit.In this way,the D-CRLH resonator can be designed according to equivalent circuit;(c)propose the synthesis design method for D-CRLH resonator,based on which the resonator can be designed with high design flexibility.The resonator can operate from microwave to millimeter-wave,while with controllable bandwidth and spurious frequency.These works have been published in IEEE Transactions on Circuits and Systems ?:Express Briefs and2015 International Workshop on Electromagnetics:Applications and Student Innovation Competition(iWEM).2.Design method for filtering circuits based on coupling matrix method and D-CRLH resonators.(a)Propose a design method for filtering circuits by merging the coupling matrix method and D-CRLH resonators.The valid range of coupling matrix method can be highly improved by adjusting the characteristics of adopted D-CRLH resonators;(b)propose a series of filtering circuits with a large range control to multiple properties,such as controllable center frequency(1 to 40 GHz),controllable bandwidth(9%to 27%),controllable stopband suppression(2f₀ to 5f₀),controllable center frequency ratio(1.6 to 3.2)and bandwidth ratio(0.52 to 2.52)for dual-band filters,and etc.;(c)significant size reduction is realized for the proposed filtering circuits,while with low insertion loss,good selectivity,and wide stopband suppression.These works have been published in IEEE Transactions on Microwave Theory and Techniques,IEEE Microwave and Wireless Components Letters,2017 Sixth Asia-Pacific Conference on Antennas and Propagation(APCAP),and etc.3.Design method of D-CRLH filtering power dividers based on miniaturized circuit topology.(a)Propose a miniaturized circuit topology for filtering power divides by removing the generally used quarter-wavelength transmission lines.The 90-degree impedance inverter is realized by the coupling effect of input external quality factor,and the whole circuit size of D-CRLH filtering power divider is only around 0.1?_g×0.1?_g;(b)propose the impedance matching technique and a miniaturized isolation circuit for filtering power divider based on external quality factors.Good impedance matching and output isolation can be both realized for the miniaturized filtering power dividers;(c)propose high-isolation filtering power dividers by using complex impedance and multiple isolation elements,whose values can be derived analytically based on equivalent circuit;(d)propose the enhancement technique to output isolation by suppressing the surface wave and air coupling,resulting in high isolation(>35 dB)and big isolation bandwidth(>500%).These works have been published in IEEE Transactions on Microwave Theory and Techniques,2018 Asia-Pacific Microwave Conference(APMC),and etc.4.Investigation of the compact and low-loss packaging/on-chip filtering circuits aiming at 5G application.(a)Aiming at the requirements of 5G systems,propose a series of packaging/on-chip filters and on-chip filtering circuits based on LTCC,Ga As,or Ga N process.Small size(usually smaller than 1×1 mm²),low insertion loss(usually smaller than 1 dB),wide stopband suppression,and high selectivity can be all realized within the millimeter-wave band;(b)propose the topology of hybrid lumped and distributed resonator for multi-layer LTCC or semiconductor process;(c)propose the realization method of multiple transmission zeroes based on mixed couplings;(d)propose the idea of reconfigurable resonator based on FET,and further improve the properties of filtering circuits(the isolation of filtering switch>60 dB)by effectively merging the passive and active circuit.These works have been submitted to IEEE Access,IEEE Transactions on Circuits and Systems II:Express Briefs,and etc.