Tokihiro Nishihara

Bio: Tokihiro Nishihara is an academic researcher from Fujitsu. The author has contributed to research in topics: Resonator & Electrode. The author has an hindex of 22, co-authored 83 publications receiving 1568 citations. Previous affiliations of Tokihiro Nishihara include Taiyo Yuden.

Development of Piezoelectric Thin Film Resonator and Its Impact on Future Wireless Communication Systems

Abstract: The bulk acoustic wave filter composed of piezoelectric thin film resonators has many features superior to those of other small filters such as a surface acoustic wave (SAW) filter and a ceramic filter. As it has no fine structure in its electrode design, it has a high Q factor that leads to low-loss and sharp-cut off characteristics and a high power durability particularly in the high-frequency range. Furthermore, it has the potentiality of integrated devices on a Si substrate. In this paper, we review the recent developments of piezoelectric thin film resonator filters in the world, including our development for mobile communication applications. After describing the feature and history of the piezoelectric thin film resonator filters, our technologies are introduced in focusing on the resonator structures, the piezoelectric thin film and electrode film materials, the cavity structures, the filter structure and its design rules and characteristics, comparing with SAW filters. The competition and coexistence between the piezoelectric thin film resonator filters and the SAW filters are also described. In this paper, we describe the development of a piezoelectric thin film resonator from the standpoint of researchers who have a long experience of SAW filter development.

Development of low-loss band-pass filters using SAW resonators for portable telephones

Abstract: A bandpass filter using surface acoustic wave (SAW) resonators in a ladder circuit structure for portable telephone systems is reported. For filter design, a simulation tool is used to consider the effects of electrodes (their apertures, the number of paired elements, thickness, and bulk wave radiation). Filter input and output impedance conditions are designed by the resonator capacitance to match the line impedance. The insertion loss and stopband rejection values are traded off against each other and are controlled by the ratio of capacitances between the parallel arm and series arm resonators, 800-MHz and 1.9-GHz band filters mounted in 3.8 mm*3.8-mm*1.5-mm ceramic packages were fabricated. They are suitable for surface mount technology (SMT). Typical frequency response characteristics are 2.5-dB maximum insertion loss in the 25-MHz passband and a stopband rejection of 25 dB. >

Piezoelectric thin-film resonator and filter

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode located to sandwich the piezoelectric film; a load film formed from patterns in a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, wherein the patterns are formed so as to surround a center of the resonance region and intersect with a pathway extending from the center to an outer periphery of the resonance region.

Piezoelectric thin-film resonator and filter using the same

Abstract: A piezoelectric thin-film resonator includes a substrate, a lower electrode arranged on the substrate, a piezoelectric film arranged on the lower electrode, and an upper electrode arranged on the piezoelectric film A region in which the upper electrode overlaps with the lower electrode through the piezoelectric film has an elliptical shape, and a condition such that 1

High performance and miniature thin film bulk acoustic wave filters for 5 GHz

Abstract: Fujitsu has developed high-performance, miniature aluminum nitride (AlN) thin Film Bulk Acoustic Resonators (FBAR) filters for 5-GHz Wireless Local Area Network (WLAN) applications. Filters with higher frequencies of around 5 GHz and wider bandwidths will be needed in future mobile communication systems. Therefore, we developed filters using thin-film Bulk Acoustic Wave (BAW) technology, which shows promise as a possible solution to these higher frequency applications. There are two issues related to the development of FBAR filters. The first has been the need for miniaturization. To achieve this, we developed a new resonator configuration that employs bulk micromachining techniques. The second issue has been to increase the bandwidth. Five-GHz WLAN applications require a 200-MHz bandwidth at 5250 MHz, which corresponds to a fractional bandwidth of 3.8%. However, the piezoelectric coupling coefficient (k/sup 2/) of AlN cannot satisfy this requirement. To achieve wider filter bandwidth, we developed two approaches. They utilize epitaxial AlN film-growth and reactance-controlled flip-chip package design technologies. The packaging technology also enabled us to miniaturize the filters.

Surgical Stapling Apparatus

Abstract: A loading unit for use with a surgical stapling apparatus is provided and includes a tool assembly having a cartridge assembly and an anvil assembly that are movable in relation to one another; a surgical buttress releasably secured to a tissue contacting surface of the anvil assembly and/or the cartridge assembly, wherein each surgical buttress is secured to the anvil assembly and/or the cartridge assembly by at least one anchor; a release assembly associated with the anvil assembly and/or the cartridge assembly; and a drive assembly slidably translatable through the tool assembly between proximal and distal positions, wherein the drive assembly actuates the release assembly to thereby release the anchor to free the surgical buttress from the anvil assembly and/or the cartridge assembly.

Annular adhesive structure

Abstract: An apparatus for forming an anastomosis between adjacent intestinal sections of tissue is provided. The apparatus includes a circular surgical stapler having an anvil assembly with an anvil shaft and an anvil, the circular surgical stapler further having a tubular body portion with an annular knife and a body portion shaft selectively attachable to the anvil shaft; and a seal structure for deposition between the intestinal sections of tissue including a hub configured to engage attachment structure on at least one of the anvil shaft and the body portion shaft. The attachment structure is positioned so that the seal structure is located between the intestinal sections of tissue when the circular surgical stapler is disposed within the intestinal sections of tissue.

Buttress and surgical stapling apparatus

Abstract: Multilayer structures including a porous layer and a non-porous layer are useful as buttresses when associated with a surgical stapling apparatus.

Staple buttress retention system

Abstract: A surgical stapling instrument is provided having systems for securing buttress material to the anvil and staple containing cartridge associated with the surgical instrument. The system includes a retainer configured to engage the anvil or the staple containing cartridge and capture the buttress material between the retainer and the anvil or staple containing cartridge. The disclose retainer engages the anvil or staple containing cartridge in snap fit or friction fit fashion. The buttress material includes a circumferential perforation line enabling the center of the buttress material to be stapled to tissue while the remainder of the buttress material remains with the anvil or staple containing cartridge.

Detachable buttress material retention systems for use with a surgical stapling device

Abstract: Systems of releasably connecting staple line buttress material to the jaws of a surgical stapling instrument are provided. The systems include retainers configured to engage the buttress material and releasably retain the buttress material on the jaws of the surgical stapling instrument prior to stapling tissue. In certain embodiments, the retainers remain with the jaws of the instrument after stapling of tissue. In alternative embodiments, the retainers remain with the buttress material after being stapled to tissue.