Research And Design Of Filter And Switch Circuit Based On SISL

With the rapid development of wireless communication technology,the research on filters and microwave switch circuits in radio frequency（RF）transceivers become more and more important.As a basic frequency selection device,the performance of the filter determines the performance of the entire transceiver system.Therefore,low insertion loss,high passband selectivity,and wide stopband suppression are the devel-opment direction of high-performance filters all along.Moreover,to achieve multiple communication modes operating simultaneously,the research of wideband and multi-band filters has attracted more and more attention.As a control device of RF signal,microwave switch circuits are widely used to select the RF path and improve the isola-tion.Among all the switch circuits,PIN diode-based switch circuits have become a hot issue in recent years due to their high power handling ability and low insertion loss.Based on the low loss,self-packaged,and high Q substrate integrated suspended line（SISL）,this thesis has carried out the research and design of filters and microwave switch circuits from two aspects of low loss and high performance,and the main work of the thesis contains the following two contents:1.Design of multiple transmission zeros（TZs）filters based on SISL.To solve the problem of the large size and high insertion loss of traditional patch resonators,a new type of shorted-stub-loaded patch resonator and a ring shorted stepped-impedance res-onator are proposed.The proposed wideband filter achieves a compact size and low insertion loss by using double-layer wiring and substrate excavation.The measured re-sult shows that the fractional bandwidth of the third-order bandpass filter centered at0.94 GHz is 45.7%.The return loss and insertion loss of the bandpass filter are 20 d B and 1.56 d B.The bandpass filter generated five TZs at the stopband,which results in a wide stopband rejection.The 20 d B rejection bandwidth is up to 5 GHz（5f₀）and the size of the bandpass filter is 0.13λ_g×0.16λ_g.Under the premise of the above research,a new slotted patch resonator is proposed.Based on the slotted patch resonator,a high isolation dual-band bandpass filter（DBBPF）is designed and fabricated.The simulated and measured results of the DBBPF show that the filter generates five poles at the pass-bands and six controllable TZs at the stopband.The isolation between the two pass-bands is better than 45 d B and the size of the DBBPF is 0.14λ_g×0.15λ_g.2.Design of low loss switch circuits based on SISL.Based on PIN diodes,a 0.5-2.5 GHz single-pole single-throw（SPST）switch circuit is designed on SISL platform.Especially,the insertion loss of the SPST is reduced by loading an LC compensation circuit.The return loss of this SPST switch is better than 15 d B and the insertion loss of this SPST switch is only 0.56 d B.The isolation of this SPST switch on off-state is better than 20 d B.Under the premise of the above research,aiming at the problem of the impedance discontinuity caused by two RF paths sharing one input terminal,an input impedance matching circuit is proposed.Based on the matching circuit,a 0.5-2.2GHz single-pole double-throw（SPDT）switch circuit is designed.The return loss of this SPDT switch is better than 15 d B and the insertion loss of this SPDT switch is 0.6 d B.The isolation of this SPDT switch on off-state is better than 25 d B and the size of this SPDT switch is only 0.08λ_g×0.16λ_g.