High-Isolation SAW Duplexer With On-Chip SAW Compensation Circuit Optimized for Isolated Multiple Frequency Bands.

This article describes the simulation analysis and experimental verification of a new type of high-isolation surface-acoustic wave (SAW) duplexer by using an SAW on-chip compensation circuit designed to cancel the leakage signal of the main SAW duplexer at multiple frequency bands. First, an analysis of amplitude and phase change of the SAW duplexer consists of a ladder-type transmitter (Tx) filter, and the double-mode SAW (DMS) receiver (Rx) filter is applied to clarify the cancellation conditions. Then, the feasibility of the SAW compensation circuit using a three-interdigital transducer (IDT) DMS resonator specially designed to satisfy the cancellation conditions is studied in circuit simulation based on the coupling-of-mode (COM) theory. Finally, we analyzed this concept in detail for a long-term-evolution (LTE) Band-I SAW duplexer for Tx and Rx band isolation in both a circuit simulation and experiment. Results showed that around 10-dB improvement of isolation in both the Tx and Rx bands was obtained without sacrificing other properties (e.g., insertion loss and attenuation) and that it agrees well with the result obtained by simulation analysis. These results are expected to be useful for now, considering that future mobile systems demand higher Rx sensitivity in multiple frequency bands.

Correlation between propagation loss and silicon dioxide film properties for surface acoustic wave devices.

The correlation between the propagation loss and SiO2 film properties has been studied for temperature-compensated SAW devices using the SiO2/LiNbO3 structure. The SAW devices were prepared under different deposition temperatures for SiO2 film. Although they possessed excellent temperature coefficient of elasticity characteristics, devices prepared at lower temperature showed lower Q-factors. The SiO2 films were also deposited on a Si substrate under the same deposition conditions used for the SAW device preparation. Optical characterization was performed with Fourier transform infrared spectroscopy (FT-IR), spectrometer measurement, and Raman spectroscopy. IR absorbance spectra were almost same in the FT-IR measurement. However, optical attenuation in the UV region decreased with the deposition temperature in the spectrometer measurement. The optical attenuation is caused by the increase of the extinction coefficient in the SiO2 layer, and its optical wavelength dependence indicated that observed excess attenuation is caused by Rayleigh scattering. The Raman scattering also decreased with the deposition temperature in the Raman spectroscopy. The scattering is caused by the distortion of the SiO2 network. These results indicate that the Rayleigh scattering caused by the distortion of the SiO2 network is the main contributor to the excess SAW propagation loss in this case.

A thin-film bulk acoustic resonator and filter with optimal edge shapes for mass production.

The manufacturing conditions of a thin-film bulk acoustic resonator (FBAR) filter were investigated to obtain a high Q factor which is stable for mass production. The FBAR consist of patterned electrodes and piezoelectric films. In this study, the influence of edge shape of the films on the anti-resonance characteristics was investigated using a numerical method. Optimized shape was applied to a 2.5-GHz band resonator and filter. As a result, significant improvement of the Q factor and the insertion loss was confirmed.

New humulenes from Hyptis incana (Labiatae).

Two new humulene-type sesquiterpenes, named hyptishumulene I (1) and II (2), have been isolated, together with eight known compounds, a humulene-type sesquiterpene (3), a monoterpene (4) and six abietane-type diterpenoids (5-10) from the aerial parts of Hyptis incana (Labiatae). The cytotoxic activity of the isolated compounds against mouse leukemia cells (L1210) was examined. The abietane-type diterpenoids (5-10) showed rather potent growth inhibitory activity (IC50<15 microM), while the new humulene-type compounds (1 and 2) exhibited moderate activity (IC50>50 microM).

Phenolic diterpenes derived from Hyptis incana induce apoptosis and G(2)/M arrest of neuroblastoma cells.

BACKGROUND: Neuroblastoma is one of the most commonly encountered solid tumors in the pediatric age group, and the prognosis of patients with advanced neuroblastoma is very poor. In this study, the antitumor effects of five phenolic diterpenes derived from Hyptis incana (Lamiaceae), a Brazilian medicinal plant, were examined on neuroblastoma cells. MATERIALS AND METHODS: Cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptotic nuclear shrinkage was monitored by Hoechst 33342 staining. The cell-cycle status was evaluated by flow cytometry and protein alterations were monitored by western blotting. Differentiated cells were photographed and counted in a randomized fashion. RESULTS: All of the examined compounds exhibited significant cytotoxicity towards the neuroblastoma cells. In particular, 7-ethoxyrosmanol had a high degree of efficacy. Nuclear condensation and degradation of procaspase-3 and -9 were observed after treatment of the cells with these compounds. Moreover, phenolic diterpenes induced cell-cycle arrest in the G(2)/M phase. Rosmanol and epirosmanol tended to induce differentiation. CONCLUSION: Phenolic diterpenes isolated from H. incana have multiple antitumor effects on neuroblastoma cells.

Use of fluorine-doped silicon oxide for temperature compensation of radio frequency surface acoustic wave devices.

This paper investigates acoustic properties, including the temperature coefficient of elasticity (TCE), of fluorine-doped silicon oxide (SiOF) films and proposes the application of the films to the temperature compensation of RF SAW devices. From Fourier transform infrared spectroscopy (FT-IR), SiOF films were expected to possess good TCE properties. We fabricated a series of SAW devices using the SiOF-overlay/Cu-grating/LiNbO(3)-substrate structure, and evaluated their performance. The experiments showed that the temperature coefficient of frequency (TCF) increases with the fluorine content r, as we expected from the FT-IR measurement. This means that the Si-O-Si atomic structure measurable by the FT-IR governs the TCE behavior of SiO(2)-based films even when the dopant is added. In comparison with pure SiO(2) with the film thickness h of 0.3 wavelengths (λ), TCF was improved by 7.7 ppm/°C without deterioration of the effective electromechanical coupling factor K2 when r = 3.8 atomic % and h = 0.28λ. Fluorine inclusion did not obviously influence the resonators' Q factors when r < 8.8 atomic %.

Correlation between temperature coefficient of elasticity and fourier transform infrared spectra of silicon dioxide films for surface acoustic wave devices.

We investigated the correlation between the temperature coefficient of elasticity (TCE) and Fourier transform infrared (FT-IR) absorption spectra of SiO(2) for SAW devices. The measurement indicated that the TCE is strongly correlated with peak frequencies; that is, with the fractional change of the Si-O-Si bond angle with temperature.

A circuit model for nonlinear simulation of radio-frequency filters using bulk acoustic wave resonators.

This paper describes a circuit model for the analysis of nonlinearity in the filters based on radiofrequency (RF) bulk acoustic wave (BAW) resonators. The nonlinear output is expressed by a current source connected parallel to the linear resonator. Amplitude of the nonlinear current source is programmed proportional to the product of linear currents flowing in the resonator. Thus, the nonlinear analysis is performed by the common linear analysis, even for complex device structures. The analysis is applied to a ladder-type RF BAW filter, and frequency dependence of the nonlinear output is discussed. Furthermore, this analysis is verified through comparison with experiments.

Ultra-steep cut-off double mode SAW filter and its application to a PCS duplexer.

This paper describes the double mode surface acoustic wave (DMS) filter design techniques for achieving the ultra-steep cut-off characteristics and low insertion loss required for the Rx filter in the personal communications services (PCS) duplexer. Simulations demonstrate that the optimal combination of the additional common ground inductance Lg and the coupling capacitance Cc between the input and output terminals of the DMS filters drastically enhances the skirt steepness and attenuation for the lower frequency side of the passband. Based on this result, we propose a novel DMS filter structure that utilizes the parasitic reactance generated in bonding wires and interdigital transducer (IDT) busbars as Lg and Ce, respectively. Because the proposed structure does not need any additional reactance component, the filter size can be small. Moreover, we propose a compact multiple-connection configuration for low insertion loss. Applying these technologies to the Rx filter, we successfully develop a PCS SAW duplexer.

Analysis and suppression of side radiation in leaky SAW resonators.

This paper discusses side acoustic radiation in leaky surface acoustic wave (LSAW) resonators on rotated Y-cut lithium tantalite substrates. The mechanism behind side radiation, which causes a large insertion loss, is analyzed by using the scalar potential theory. This analysis reveals that side radiation occurs when the guiding condition is not satisfied, and the LSAW most strongly radiates at the frequency in which the LSAW velocities in the grating and busbar regions approximately correspond to each other. Based on these results, we propose a "narrow finger structure," which satisfies the guiding condition and drastically suppresses the side radiation. Experiments show that the resonance Q of the proposed structure drastically improves to over 1000 by suppressing the side radiation, which is three times higher than for a conventional structure. Applying the proposed resonators to the ladder-type SAW filters, ultra-low-loss and steep cut-off characteristics are achieved in the range of 800 MHz and 1.9 GHz.

Studies on panax acetylenes: absolute structure of a new panax acetylene, and inhibitory effects of related acetylenes on the growth of L-1210 cells.

A new Panax acetylene, 3-oxo-PQ-1 (1), was isolated from Panax quinquefolium. The absolute configurations of 3-oxo-PQ-1 (1) and PQ-1 (2) were determined to be (9R,10R) and (3R,9R,10R), respectively, by synthesizing 1 and 2 starting from D-(-)-diethyl tartrate, and by synthesizing their stereoisomers from L-(+)-diethyl tartrate. The growth inhibitory effects of Panax acetylenes (1-8) and their stereoisomers against leukemia cells were tested. Unnatural acetylenes having the (3S)-configuration (2, 5, 6, 7, 8; IC(50)=0.01-0.1 microg/ml) were found to be approximately ten times more potent than natural acetylenes (IC(50)=0.1-1.0 microg/ml) with the (3R)-configuration. Potency differences due to the configuration at C-9 and C-10 were unrelated to this stereochemistry. The C(14)-polyacetylenes, PQ-8 (4) and its isomer (IC(50)=1.0-10.0 microg/ml), were found to exhibit weaker cytotoxicity than the C(17)-polyacetylenes.

Studies on the constituents of Leonurus sibiricus L.

Two new furanoditerpene-lactones, LS-1 (1) and LS-2 (2), were isolated along with four known furanoditerpene-lactones 3, 4, 5 and 6 from the aerial part of Leonurus sibiricus L. The structures of the new compounds were determined by spectroscopic means. Compounds 1-6 isolated here exhibited moderate cytotoxic activity (IC(50)=50-60 microg/ml) against leukemia cells (L 1210) in tissue culture.