• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.3
• /
• pp.284-290
• /
• 2004

In this paper, two types of thin nim bulk acoustic resonator(TFBAR) ladder filters are desisted and fabricated to analyze the effects of on-wafer inductor integration. To suppress the overmode phenomenon a 1 $\mu\textrm{m}$ thick air-gap is fabricated under the TFBAR and aluminum nitride is used for piezoelectric material, while platinum is employed for the top and bottom electrodes. The Tx filter in a duplexer, which usually has a steeper skirt characteristics o the right side of the passband, is designed with four serial and two shunt resonators, namely, a 4/2 stage. Similarly, the Rx filter is devised with a 3/4 stage to create a mirrored image of the Tx filter passband characteristics. Fabricated on-wafer spiral inductors with underpass reveals the Q factor of 5～9 at 2 ㎓. Inductor integrated filters have approximately 10 to 12 ㏈ out-of-band rejection improvement, when compared to the original filters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.10
• /
• pp.1048-1053
• /
• 2002

In this paper, thin film bulk acoustic resonator(TFBAR) lattice and balanced type filter topologies are designed and fabricated. Aluminium nitride and platinum are used for piezoelectric material and top and bottom electrodes, respectively. Air-gap is placed to avoid silicon substrate loading effect and the performance of these lattice and balanced filters is compared with ladder filters. These filters have selectivity over 15 dB for lattice type and 30 dB for balanced type and reveal wider bandwidth of the ladder filters. For balanced type filters, minor tuning procedure is not needed and they are readily available for RF filter in wireless applications.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.3
• /
• pp.10-17
• /
• 2003

In this paper, genetic algorithm (GA)-based Thin Film Bulk Acoustic Resonator (FBAR) RF filter design technique is proposed. Since the BVD(Butterworth-Van Dyke) lumped element model is valid only around the resonance, FBAR filter design technique based on BVD circuit has an approximate error. Instead of using BVD model, optimizing filter design method utilizes an analytical electrical impedance equation of FBAR. The geometry of FBAR such as thickness of the piezoelectric layer and area which significantly affect the filter response is optimized by GA. US-PCS Rx Bandpass filter obtained by the proposed technique shows a better response comparing with the typical and BVD-based filter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.1
• /
• pp.103-109
• /
• 2004

In this paper, a new modeling methodology of thin film bulk acoustic resonator(TFBAR) is presented and the formulations of each lumped element in the model are also introduced. The new model is based upon the Mason model that is a reasonable model to explain the physical characteristics of unit TFBAR. After simplifying the modified Mason model with an additional dielectric loss term, the new model similar to Modified Butterworth-Van Dyke(MBVD) model is complete. The proposed model has three optimization variables which is half of the MBVD model. As a result, the curve fittings for the measured data are much faster and more accurate than any other conventional models. Moreover, it is very useful to design the bandpass filters or voltage controlled oscillators due to the design parameters, such as resonant and anti-resonant frequency, which can reflect the intentions of designer in the model.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.3-6
• /
• 2002

In this paper, Thin film bulk acoustic resonate.(TFBAR) fillers tuned by gold plated on-wafer inductors are presented. The air-gap type TEBAR is used with aluminum nitride(AIN) as piezoelectric material and platinum as top and bottom electrodes. Inductor equivalent model and modified Butterworth-Van Dyke(MBVD) model are employed for the frequency tuning of fabricated TFBAR bandpass filters. Fabricated inductor has inductance of 3 nH and Q factor of about 8 at 2 ㎓. It is clearly revealed that inductor tuning can enhance the bandwidth of ladder filters and improve out-of-band rejection characteristic around 10㏈.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.12
• /
• pp.139-145
• /
• 2008

In this paper, a microstrip surface wave antenna(SWA) with a frequency selective surface structure(FSS) is designed and measured. A microstrip SWA has many advantages such as low profile, low weight, easy fabrication, and compatibility with monolithic microwave integrated circuits(MMIC). In addition, it has demonstrated monopole like beam patterns. The microstrip SWA consists of two parts : a center-fed modified microstrip patch to excite surface wave, and a periodic patches to support the propagation of the surface waves. To obtain wide bandwidth, the ring type parasitic element is inserted and the circular patch is selected for the unit element in FSS structure. Experimental results show that the microstrip SWA has monopole like beam patterns at 5.9GHz. Impedance bandwidth and gain is 12% and 5.6dBi.