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

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.173-177
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• 2003

In this paper, a new modeling methodology of thin film bulk acoustic resonate. (TFBAR) is presented. The new model is started from the Mason model that is a good model to explain the physical characteristics of TFBAR. After simplifying the modified Mason model added dielectric loss term to conventional Mason model, the improved Modified Butterworth-Van Dyke (MBVD) model similar to conventional MBVD model is complete. The proposed model has three optimization variables those are half of the MBVD model. As a result, the curve fittings for the measured data are faster and smarter than any other model.

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

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.34-38
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• 2002

TFBAR filters for wireless applications are simulated and fabricated. A CAD model is used to analize the air-gap type single resonator and MBVD model is used far filter design. Aluminum nitride is used as the piezoelectric material with platinum electrodes. To verier the CAD model, simulated and measured results are compared far various top electrode thicknesses, and the agreement is within 0.5 % for the parallel resonance frequency. Various types of the ladder type band pass filters are predicted and their responses are compared with measured frequency data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.284-290
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• 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
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• v.13 no.10
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• pp.1048-1053
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• 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.