Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193561
J. Ella, M. Ylilammi
This paper proposes a method to simulate the center frequency shift in bulk acoustic wave (BAW) filters, caused by high input signal levels, which heat up the devices. The results were verified by wafer level measurements and on diced devices wire bonded to jigs. In addition the temperature distribution on diced samples was imaged with an infrared camera. The measured and calculated center frequency shifts as well as the temperature distribution in filters correlate fairly well.
{"title":"Modelling of ZnO-based BAWs at high signal levels","authors":"J. Ella, M. Ylilammi","doi":"10.1109/ULTSYM.2002.1193561","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193561","url":null,"abstract":"This paper proposes a method to simulate the center frequency shift in bulk acoustic wave (BAW) filters, caused by high input signal levels, which heat up the devices. The results were verified by wafer level measurements and on diced devices wire bonded to jigs. In addition the temperature distribution on diced samples was imaged with an infrared camera. The measured and calculated center frequency shifts as well as the temperature distribution in filters correlate fairly well.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115291251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192516
K. Nakamura, K. Fukazawa, K. Yamada, S. Saito
Some heat treatment of a LiNbO/sub 3/ plate induces domain inversion, thereby yielding a ferroelectric inversion layer. In such a piezoelectric plate with an inversion layer, even-order thickness-extensional modes as well as odd-order modes can be excited piezoelectrically. Therefore, the ultrasonic transducer using such a piezoelectric plate is expected to operate over a wide frequency range. In this paper it is shown that broadband ultrasonic transducers can be obtained at a certain thickness ratio of inversion layer to plate and that the transducer characteristics differ depending on whether the inversion layer is on the front side or on the backside. The broadband characteristics are experimentally demonstrated by fabricating transducers with 9 MHz or 75 MHz center frequency using 36/spl deg/ rotated Y-cut LiNbO/sub 3/ plates with a ferroelectric inversion layer.
{"title":"Broadband ultrasonic transducers using a LiNbO/sub 3/ plate with a ferroelectric inversion layer","authors":"K. Nakamura, K. Fukazawa, K. Yamada, S. Saito","doi":"10.1109/ULTSYM.2002.1192516","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192516","url":null,"abstract":"Some heat treatment of a LiNbO/sub 3/ plate induces domain inversion, thereby yielding a ferroelectric inversion layer. In such a piezoelectric plate with an inversion layer, even-order thickness-extensional modes as well as odd-order modes can be excited piezoelectrically. Therefore, the ultrasonic transducer using such a piezoelectric plate is expected to operate over a wide frequency range. In this paper it is shown that broadband ultrasonic transducers can be obtained at a certain thickness ratio of inversion layer to plate and that the transducer characteristics differ depending on whether the inversion layer is on the front side or on the backside. The broadband characteristics are experimentally demonstrated by fabricating transducers with 9 MHz or 75 MHz center frequency using 36/spl deg/ rotated Y-cut LiNbO/sub 3/ plates with a ferroelectric inversion layer.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121228063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192648
R.S. Thompson, C. Macaskill, L. Farnell, W. Fraser
Vascular disease alters the shape of the lumen of a blood vessel. The lumen is not circular from the early stages of the disease, where there is intimal thickening, through to advanced stages where a large plaque may protrude into the lumen. Using a mathematical model we investigated the ultrasound intensity distribution, both within the vessel wall and across the lumen, in the presence of a simulated wall lesion. Acoustic impedance interfaces due to wall lesions have dimensions (typically /spl sim/ 1 mm) only slightly greater than the wavelength (/spl sim/ 0.3 mm for 5 MHz ultrasound). Full wave solutions for the acoustic field are therefore required. Exact solutions in terms of Bessel functions are known for the case of a cylindrical vessel, and a collocation method based on this was developed for non-circular interfaces. By considering two such interfaces we developed a novel model representation of a vessel with a simulated wall lesion. The results of this study show how vessel wall properties may alter the ultrasound intensity distribution within the vessel wall and across the lumen. In the case of non-circular impedance interfaces there can be significant effects due to the local curvature and orientation of the interface.
{"title":"Ultrasound intensity calculations for a vessel with simulated wall lesion","authors":"R.S. Thompson, C. Macaskill, L. Farnell, W. Fraser","doi":"10.1109/ULTSYM.2002.1192648","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192648","url":null,"abstract":"Vascular disease alters the shape of the lumen of a blood vessel. The lumen is not circular from the early stages of the disease, where there is intimal thickening, through to advanced stages where a large plaque may protrude into the lumen. Using a mathematical model we investigated the ultrasound intensity distribution, both within the vessel wall and across the lumen, in the presence of a simulated wall lesion. Acoustic impedance interfaces due to wall lesions have dimensions (typically /spl sim/ 1 mm) only slightly greater than the wavelength (/spl sim/ 0.3 mm for 5 MHz ultrasound). Full wave solutions for the acoustic field are therefore required. Exact solutions in terms of Bessel functions are known for the case of a cylindrical vessel, and a collocation method based on this was developed for non-circular interfaces. By considering two such interfaces we developed a novel model representation of a vessel with a simulated wall lesion. The results of this study show how vessel wall properties may alter the ultrasound intensity distribution within the vessel wall and across the lumen. In the case of non-circular impedance interfaces there can be significant effects due to the local curvature and orientation of the interface.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123855702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193485
T. Hemsel, W. Littmann, J. Wallaschek
Piezoelectric transformers are well known since the publication of some patent applications at the end of the 1950s. But until today their only business use lies in the field of backlighting systems for LCDs. Due to key features as light-weight, flatness, high step-up at low volume and high efficiency piezoelectric transformers should be usable in a much broader range of applications. This contribution returns to mind their operating principle, shows how to model and to develop such devices as well as give some aspects for development trends that will lead to further applications.
{"title":"Piezoelectric transformers - state of the art and development trends","authors":"T. Hemsel, W. Littmann, J. Wallaschek","doi":"10.1109/ULTSYM.2002.1193485","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193485","url":null,"abstract":"Piezoelectric transformers are well known since the publication of some patent applications at the end of the 1950s. But until today their only business use lies in the field of backlighting systems for LCDs. Due to key features as light-weight, flatness, high step-up at low volume and high efficiency piezoelectric transformers should be usable in a much broader range of applications. This contribution returns to mind their operating principle, shows how to model and to develop such devices as well as give some aspects for development trends that will lead to further applications.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"5 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124875910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193348
G. Martin, H. Schmidt, B. Wall
The present paper describes SPUDT cells, all fingers of which are wider than /spl lambda//8 while maintaining the unidirectional effect. The first solution is related to a SPUDT consisting of /spl lambda//4 and /spl lambda//2 wide fingers arranged in two tracks. Each track has no significant unidirectional effect. Both tracks form a waveguide and the waveguide coupling generates the interaction of the tracks. As a result of that interaction a unidirectional effect arises. It has been verified by experiment. A second solution is suggested that includes, in contrast to DART, EWC and Hunsinger cells, SPUDT cell fingers with one and the same width only. Cell types with /spl lambda//6, /spl lambda//5 and /spl lambda//3 wide fingers are considered. One of these cell types including /spl lambda//5 wide fingers only is experimentally investigated and a unidirectional effect is found. For this cell type, no waveguide coupling is required.
{"title":"New SPUDT cell structures","authors":"G. Martin, H. Schmidt, B. Wall","doi":"10.1109/ULTSYM.2002.1193348","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193348","url":null,"abstract":"The present paper describes SPUDT cells, all fingers of which are wider than /spl lambda//8 while maintaining the unidirectional effect. The first solution is related to a SPUDT consisting of /spl lambda//4 and /spl lambda//2 wide fingers arranged in two tracks. Each track has no significant unidirectional effect. Both tracks form a waveguide and the waveguide coupling generates the interaction of the tracks. As a result of that interaction a unidirectional effect arises. It has been verified by experiment. A second solution is suggested that includes, in contrast to DART, EWC and Hunsinger cells, SPUDT cell fingers with one and the same width only. Cell types with /spl lambda//6, /spl lambda//5 and /spl lambda//3 wide fingers are considered. One of these cell types including /spl lambda//5 wide fingers only is experimentally investigated and a unidirectional effect is found. For this cell type, no waveguide coupling is required.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114279868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1192643
Y. Osanai, N. Tagawa, A. Minagawa, T. Moriya, S. Minohara
Motion analysis in sonogram is used in the heavy ion radiation therapy in cancer treatment in order to decide irradiation timing. Some of the authors have proposed a method by which motion of internal organs, which is sensitive to the expansion and contraction of lung, is computed as a regression process with respect to a respiratory signal. In this method the motion is obtained with low-resolution, since this method is based on the gradient method, and then a low-pass filter should be applied to the sonogram. In this paper, multiple image sequences with different resolution at each other are hierarchically generated by applying band-pass filters. The information of the motion obtained in lower resolution image is propagated to higher resolution image, i.e., the motion is computed recursively. In the lowest stage, conventional method with an information of respiratory signal is applied. The effectiveness of the proposed algorithm is confirmed through real image experiments.
{"title":"High-resolution computation of 2-D motion from sonogram","authors":"Y. Osanai, N. Tagawa, A. Minagawa, T. Moriya, S. Minohara","doi":"10.1109/ULTSYM.2002.1192643","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1192643","url":null,"abstract":"Motion analysis in sonogram is used in the heavy ion radiation therapy in cancer treatment in order to decide irradiation timing. Some of the authors have proposed a method by which motion of internal organs, which is sensitive to the expansion and contraction of lung, is computed as a regression process with respect to a respiratory signal. In this method the motion is obtained with low-resolution, since this method is based on the gradient method, and then a low-pass filter should be applied to the sonogram. In this paper, multiple image sequences with different resolution at each other are hierarchically generated by applying band-pass filters. The information of the motion obtained in lower resolution image is propagated to higher resolution image, i.e., the motion is computed recursively. In the lowest stage, conventional method with an information of respiratory signal is applied. The effectiveness of the proposed algorithm is confirmed through real image experiments.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125234515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193401
Y. Shui, Haodong Wu, Ning Wang, Jiming Lin
There are two kinds of traditional weighting methods for SAW interdigital transducers: apodization and withdrawal weighting. The former has been abandoned in many low loss filters design on account of the additional loss due to the weighting. The latter can be used only for narrow band filters with many fingers. In order to design low loss wideband filters, we propose a new method: topological weighting. We use Green's function to calculate accurately the COM (Coupling-of-Modes) parameters of the cells with different geometry (different finger widths and different finger gaps) for so called EWC (Electrode Width Controlled) structure, i.e. there are three electrodes in one cell, one of them is applied the voltage and other two are grounded. On the 128/spl deg/ rotated LiNbO/sub 3/, we get a filter with /spl sim/6.6% bandwidth, 3.8 dB loss and >41dB sidelobe Suppression by the calculation. In the experiment, because of the bad processing technology and electrode resistance effect, we have the result with loss 5 dB, sidelobe suppression 35.8 dB and the bandwidth of 5.5%. The interdigital transducers have the dimension /spl sim/25/spl times/15 wavelengths.
{"title":"A noval weighting method for low loss SAW wideband filters: topological weighting","authors":"Y. Shui, Haodong Wu, Ning Wang, Jiming Lin","doi":"10.1109/ULTSYM.2002.1193401","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193401","url":null,"abstract":"There are two kinds of traditional weighting methods for SAW interdigital transducers: apodization and withdrawal weighting. The former has been abandoned in many low loss filters design on account of the additional loss due to the weighting. The latter can be used only for narrow band filters with many fingers. In order to design low loss wideband filters, we propose a new method: topological weighting. We use Green's function to calculate accurately the COM (Coupling-of-Modes) parameters of the cells with different geometry (different finger widths and different finger gaps) for so called EWC (Electrode Width Controlled) structure, i.e. there are three electrodes in one cell, one of them is applied the voltage and other two are grounded. On the 128/spl deg/ rotated LiNbO/sub 3/, we get a filter with /spl sim/6.6% bandwidth, 3.8 dB loss and >41dB sidelobe Suppression by the calculation. In the experiment, because of the bad processing technology and electrode resistance effect, we have the result with loss 5 dB, sidelobe suppression 35.8 dB and the bandwidth of 5.5%. The interdigital transducers have the dimension /spl sim/25/spl times/15 wavelengths.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"257 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115796778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193393
V. Laude, S. Ballandras
We address the problem of the estimation of the slowness and of the attenuation of a pseudo surface acoustic wave (PSAW) on a semi-infinite substrate. This problem is an old one and many possible solutions have been given, usually making use of a complex excitation slowness along the propagation direction. We argue that this approach gives rise to a discontinuity in the partial wave selection rule and is hence self contradictory. We then propose an alternative solution, avoiding the use of complex excitation slownesses, by analogy with the problem of the reflection of a bulk acoustic wave on the surface. Specifically, we include an optimal source term exactly compensating for the energy lost by leakage. This leads us to the minimization of a function which minimum is the PSAW slowness and which minimum value gives the attenuation.
{"title":"A least action principle for the location of PSAW's and a minimum bound on their attenuation","authors":"V. Laude, S. Ballandras","doi":"10.1109/ULTSYM.2002.1193393","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193393","url":null,"abstract":"We address the problem of the estimation of the slowness and of the attenuation of a pseudo surface acoustic wave (PSAW) on a semi-infinite substrate. This problem is an old one and many possible solutions have been given, usually making use of a complex excitation slowness along the propagation direction. We argue that this approach gives rise to a discontinuity in the partial wave selection rule and is hence self contradictory. We then propose an alternative solution, avoiding the use of complex excitation slownesses, by analogy with the problem of the reflection of a bulk acoustic wave on the surface. Specifically, we include an optimal source term exactly compensating for the energy lost by leakage. This leads us to the minimization of a function which minimum is the PSAW slowness and which minimum value gives the attenuation.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"102 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113996525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193567
A. Ballato
Poisson's ratio finds application in a number of areas of applied elasticity and solid mechanics, for example, to quantify the mechanical coupling between various vibrational modes. The gamut of future high-tech applications, e.g., resonant microstructures integrated with electronic and optical circuitry, can be extended by providing a dynamic mechanism for electrical adjustment of this quantity. This requires an extension of the usual Poisson's ratio considerations to include the piezoelectricity of anisotropic substances. For piezoelectric materials, the Poisson's ratios vary with orientation. This variability is to be expected. What is surprising is the size of the variability that can be produced via the piezo-effect by altering electrical boundary conditions in substances with strong piezocoupling, e.g., poled electroceramics. This second source of adjustment appears an attractive means of tuning novel MEMS filter and resonator devices for future cellular communications. This paper describes how both forms of variation come about: the angular changes, and how these are modified by the piezoelectric effect when electrical loads are imposed. Numerical examples are given.
{"title":"Alteration of Poisson's ratio in high coupling piezoelectrics","authors":"A. Ballato","doi":"10.1109/ULTSYM.2002.1193567","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193567","url":null,"abstract":"Poisson's ratio finds application in a number of areas of applied elasticity and solid mechanics, for example, to quantify the mechanical coupling between various vibrational modes. The gamut of future high-tech applications, e.g., resonant microstructures integrated with electronic and optical circuitry, can be extended by providing a dynamic mechanism for electrical adjustment of this quantity. This requires an extension of the usual Poisson's ratio considerations to include the piezoelectricity of anisotropic substances. For piezoelectric materials, the Poisson's ratios vary with orientation. This variability is to be expected. What is surprising is the size of the variability that can be produced via the piezo-effect by altering electrical boundary conditions in substances with strong piezocoupling, e.g., poled electroceramics. This second source of adjustment appears an attractive means of tuning novel MEMS filter and resonator devices for future cellular communications. This paper describes how both forms of variation come about: the angular changes, and how these are modified by the piezoelectric effect when electrical loads are imposed. Numerical examples are given.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127799554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-10-08DOI: 10.1109/ULTSYM.2002.1193376
H. Nakamura, S. Tsuzuki, T. Yamada, T. Ishizaki
The degradation mechanism of balance performance for balanced-type SAW filters was analyzed. The authors have confirmed that the parasitic coupling between input and output IDTs makes the balance characteristics degrade. The measurement results show good agreement with simulations by assuming the parasitic capacitances. The balance characteristics can be improved by decreasing the parasitic capacitances. Further, the much better performance can be obtained by connecting inductors between input and output IDTs. Parallel resonance circuit with additional inductor and the parasitic capacitance can solve the problem successfully. The experimental balanced-type SAW filter shows an excellent performance. These values satisfy the system requirements.
{"title":"An analysis and improvement of balanced-type SAW filters","authors":"H. Nakamura, S. Tsuzuki, T. Yamada, T. Ishizaki","doi":"10.1109/ULTSYM.2002.1193376","DOIUrl":"https://doi.org/10.1109/ULTSYM.2002.1193376","url":null,"abstract":"The degradation mechanism of balance performance for balanced-type SAW filters was analyzed. The authors have confirmed that the parasitic coupling between input and output IDTs makes the balance characteristics degrade. The measurement results show good agreement with simulations by assuming the parasitic capacitances. The balance characteristics can be improved by decreasing the parasitic capacitances. Further, the much better performance can be obtained by connecting inductors between input and output IDTs. Parallel resonance circuit with additional inductor and the parasitic capacitance can solve the problem successfully. The experimental balanced-type SAW filter shows an excellent performance. These values satisfy the system requirements.","PeriodicalId":378705,"journal":{"name":"2002 IEEE Ultrasonics Symposium, 2002. Proceedings.","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132752540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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