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dc.rightsUrheberrechtlich geschützt
dc.subjectRF MEMSeng
dc.subjecttunable capacitoreng
dc.subjectmicrowave oscillatoreng
dc.titleDevelopment of RF MEMS for Innovative Applications in Microwave Systemseng
dcterms.abstractUtilization of RF MEMS tunable capacitors in microwave circuits is rapidly growing up. A low cost and simple production of an RF MEMS tunable capacitor is increasingly demanded. Within this work an RF MEMS tunable capacitor structure with low cost materials and process is successfully developed and characterized. A new process with reduced production time and a less number of fabrication steps by incorporating isolating dielectric materials as part of the top membrane in the RF MEMS capacitor structure is presented. A capacitance tuning ratio of 2.24 from the developed RF MEMS tunable capacitor is satisfactorily achieved. A microwave voltage-controlled oscillator circuit integrating the developed RF MEMS tunable capacitor is designed and tuning of the oscillation frequency generated from the oscillator circuit is sufficiently demonstrated. Realization of the RF MEMS tunable capacitor is conducted with a conventional lithography process. The developed RF MEMS tunable capacitor consists of a membrane held by four suspensions in the topology of the fixed-fixed flexure structure. Dielectric material layers are not deposited on top of a bottom aluminum electrode, but they are combined to be part of a movable membrane. The pattern of dielectric material layers follows the top aluminum electrode accordingly. Therefore, no additional lithography process takes place to structure the dielectric material as it is required for the case when the dielectric material layers are fixed on top of the bottom aluminum electrode. From microwave structure point of view, the developed RF MEMS tunable capacitor follows coplanar waveguide topology, consisting of a trace line and two ground lines surrounding the trace line. Both ground lines are connected by a movable membrane and four suspensions. Dimension of the movable membrane is 140 μm by 140 μm. A DC bias voltage is applied between top and bottom electrodes of the RF MEMS tunable capacitor via bond wires to control the height of the membrane, so that the capacitance varies accordingly. The capacitance of the RF MEMS capacitor is tunable from 326 fF to 730 fF by applying DC bias voltage of 0 V to 90 V, respectively. The developed RF MEMS is integrated into a microwave oscillator circuit, whereas the variation of the tuned capacitance of RF MEMS determines the oscillation frequency of the microwave oscillator circuit. As comparison, a varicap-based voltage-controlled oscillator circuit is also designed and realized. Lower power drift and lower phase noise at Δf = 1 MHz are shown by the voltage-controlled oscillator with RF MEMS tunable capacitor.eng
dcterms.accessRightsopen access
dcterms.creatorChatim, Ruddy Herard
dc.contributor.corporatenameKassel, Universität Kassel, Fachbereich Elektrotechnik / Informatik
dc.contributor.refereeBangert, Axel (Prof. Dr.)
dc.contributor.refereeHillmer, Hartmut (Prof. Dr.)

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