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Summary form only given. Al-electrodes on 36-48°YX-LiTaO3 substrates have been widely used in surface acoustic wave (SAW) filters and SAW duplexers because of having an optimum electro-mechanical coupling factor, reflection coefficient and good Q-factor. In this paper, authors proposed and constructed a new SAW structure composed of upper Al-electrodes accumulated on lower grooved Cu-electrodes in...
High-frequency devices operating at 3 GHz or higher are required, for instance, for future 4th generation mobile phone systems in Japan. Using a substrate with a high acoustic velocity is one method to realize a high-frequency acoustic or elastic device. A Lamb wave has a high velocity when the substrate thickness is thin. To realize a high-frequency device operating at 3 GHz or higher using a Lamb...
A highly accurate strain sensing system has been developed by combining an acoustic optic tunable filter (AOTF), an optical fiber, and fiber Bragg gratings (FBGs). The AOTF is composed of an interdigital transducer (IDT) to generate surface acoustic wave (SAW), a SAW guide, and polarization beam splitters (PBSs) for separating TE and TM modes from a light with both modes and optical waveguides consisting...
A high frequency device of 3 GHz or more is required, for instance, for future 4-th generation mobile phone system in Japan. Using a substrate with a high velocity is one method to realize a high frequency elastic device. A lamb wave has a high velocity when the substrate thickness normalized by a wavelength (lambda) of an elastic wave is thin. It is difficult to make a very thin crystal plate in...
Though acoustic wave devices using a periodical poled Pb(Zix, Ti1-x)O3 (PZT) ceramic plate on Si substrate, a periodical poled Pb(Zr0.2Ti0.8)O3 thin film on (001)SrTiO3 substrate, and a periodical poled Z-LiNbO3 substrate have been reported, their frequency responses were very weak as 0.1 to 3 dB. It is considered that because their periodical poled devices have neither electrode fingers of intergidital...
It has been considered that it is difficult to realize higher frequency devices than 3 GHz by using conventional surface acoustic wave (SAW) substrate. In order to realize a high frequency device, there are some methods such as using a high velocity substrate or shortening a wavelength (lambda) of an interdigital transducer (IDT). However, almost of all conventional SAW substrates have a low velocity...
Authors have already realized 3.0times2.5times1.2 or 2.5times2.0times0.48 mm3 size SAW duplexers for personal communication services in US with an excellent temperature coefficient of frequency (TCF) by using the Rayleigh wave on the SiO2/Cu-electrode/ 120deg-128degYX-LiNbO3 and 36deg-48degYX-LiTaO3 structures. This time, authors intentionally attempted to make the convex portions on the SiO2 film...
The Lamb wave type of high frequency resonator was proposed. But any Lamb wave resonator operating really above 3 GHz, which is difficult to be realized with conventional surface acoustic wave (SAW), have been not reported. Authors have tried to realize the high frequency device by using A1 mode of Lamb wave propagating in the X-axis direction on Z-cut thin LiNbO3 film deposited by chemical vapor...
This paper reviews physical properties of piezoelectric boundary acoustic waves (PBAWs) and their application to miniature and high performance RF filters. First, basic properties of PBAWs are discussed. It is shown that PBAWs are supported in various structures provided that highly piezoelectric material(s) are employed as structural member(s). For example, PBAWs are trapped near the electrode region...
Radio frequency (RF) filters in high frequency using surface acoustic wave (SAW) such as MediaFLOTM, time division synchronous code division multiple access (TDSCDMA) in China handy phone system, and global positioning system (GPS) in cars require a narrow bandwidth. So, the SAW substrates for their RF filters are also required to have a very excellent temperature coefficient of frequency (TCF) and...
In this paper, we propose two new voltage calculation methods for fast torque response of IPMSM in voltage saturation region, which are maximum torque response method and constant current response ratio method. Compared with the usual methods, which are constant phase angle method, constant back emf method and constant d-axis voltage method, the proposed methods give faster torque response confirmed...
Small sized surface acoustic wave (SAW) duplexer for wide band code division multiple access (W- CDMA) system with a good temperature coefficient of frequency (TCF) and good frequency characteristics has been required. However, the size of conventional SAW duplexer for W-CDMA using Al-electrode/50-70degYX- LiNbO3 is large (3.8x3.8 mm2) and its TCF is not good (-80ppm/degC). So, this duplexer can't...
Using flattened-SiO2/Cu-electrode/36~48deg LiTaO3 structure, small size (5 x5mm2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US-PCS was realized by authors. However, a smaller duplexer has been strongly required. Using flip-chip bonding process of SAW chips and Rayleigh SAW propagating on the flattened-SiO2/Cu- electrode/126~128degYX-LiNbO3, which...
Currently, miniature surface acoustic wave (SAW) devices (filters and duplexers) with a good temperature stability are strongly required. In order to realize its requirement, various SAW substrates combining a high density metal electrode and a substrate were researched. Combination of SAW substrates using high density metal electrodes offers excellent properties such as large electrode reflection...
Currently, some surface acoustic wave (SAW) devices, especially duplexers, are required to have a good temperature coefficient of frequency (TCF), because the bands between a transmission band (Tx) and a receiving band (Rx) of the duplexer such as personal communication services (PCS) mobile phone in US is very narrow (about 1%). However, a 36-48degYX-LiTaO3 substrate, which is used for most SAW radio...
This paper describes the novel current control system of interior permanent magnet synchronous motor (IPMSM) based on model predictive control (MPC). Proposed current controller directly selects one of the switching modes of PWM inverter instead of generating voltage reference as conventional one. The problem with selecting the switching mode to output is formulated as MPC problem, considering actual...
For high performance and wide speed range control of an IPMSM, using the overmodulation range of an inverter is one of the effective methods. However, to use this overmodulation range with the closed loop currents control system, there are many problems occur and the main problem is caused by the harmonic currents generated from harmonic voltages in the inverter output voltages. Therefore, in the...
In this paper, we propose the method of inverter modeling for linearization of PMSM current control system in the overmodulation range. Because of the nonlinear characteristic and the large amount of harmonic components when an inverter is operating in the overmodulation range, it's quite difficult to use the usual linear current controller design methods. For counteracting this problem, we considered...
Authors report a new structure of a shear horizontal (SH) type boundary acoustic wave for cellular phone applications. Such a structure composed of electrodes with a low shear wave velocity between two materials, namely, the SiO2 film/high density electrode/LiNbO 3 substrate, is proposed. The unique feature of this structure is that it does not require a cavity on the substrate surface. The ladder...
Most surface acoustic wave (SAW) radio frequency (RF) filters and duplexers have the Al-electrodes/36-48degYX-LiTaO3 substrate structure, which has an optimum coupling factor and an optimum reflection coefficient but does not have a good temperature coefficient of frequency (TCF). The TCF can be improved by depositing SiO2 film with positive TCF on a transversal SAW filter consisting of a substrate...
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