Agilent Technologies

About: Agilent Technologies is a company organization based out in Santa Clara, California, United States. It is known for research contribution in the topics: Signal & Mass spectrometry. The organization has 7398 authors who have published 11518 publications receiving 262410 citations. The organization is also known as: Agilent Technologies, Inc..

Power handling and temperature coefficient studies in FBAR duplexers for the 1900 MHz PCS band

Abstract: Duplexers for 1900 MHz PCS handsets based on FBARS have been realized by micro-machined thin film AlN devices. A major advantage of the FBAR duplexer is a 10-fold reduction in physical volume compared to that of dielectric types. However, since the RF input power to the transmit (Tx) filter remains at levels up to +29 dBm input, the Poynting power density is /spl sim/1 kWatts/cm/sup 2/ with concomitantly large RF strain RF levels. The in-band insertion loss for the entire multi-element Tx ladder filter is/spl sim/3 dB (343 mW dissipated maximum), which results in a volume power dissipation per FBAR/spl sim/1 MWatts/cm/sup 3/. Power densities of this order can lead to 1) frequency shifts due to heating, 2) long term degradation, 3) strain levels approaching the fracture limit of the thin films comprising the FBAR, and 4) thermal destruction of the Tx filter FBARS. We discuss two methods to measure the temperature coefficient of frequency: 1) probing individual FBAR resonators on a hot chuck, or 2) heating packaged duplexers in an oven. The measured resonator frequency temperature coefficient is/spl sim/27 ppm//spl deg/C, while the duplexer Tx response shows a somewhat lower value. Self-heating temperatures can be estimated from this and the observed frequency shift, and were also measured by infrared microscopy. Next, we present preliminary results on the duplexer power handling capabilities, based on a small sample of parts. The Tx devices will withstand up to +36 dBm (4 Watts) input power without destruction. Above this, catastrophic failures can be observed. A scanning electron micrograph example illustrating a catastrophic failure in the duplexer Tx filter will be presented. Finally, we will discuss the effects of high power (+30 to +36 dBm) on duplexer performance. At present we do NOT observe any long term, cumulative effects which could lead to catastrophic failures. Our observations support a model in which device characteristics shift slightly with time.

Differences in Vascular Bed Disease Susceptibility Reflect Differences in Gene Expression Response to Atherogenic Stimuli

Abstract: Atherosclerosis occurs predominantly in arteries and only rarely in veins. The goal of this study was to test whether differences in the molecular responses of venous and arterial endothelial cells (ECs) to atherosclerotic stimuli might contribute to vascular bed differences in susceptibility to atherosclerosis. We compared gene expression profiles of primary cultured ECs from human saphenous vein (SVEC) and coronary artery (CAEC) exposed to atherogenic stimuli. In addition to identifying differentially expressed genes, we applied statistical analysis of gene ontology and pathway annotation terms to identify signaling differences related to cell type and stimulus. Differential gene expression of untreated venous and arterial endothelial cells yielded 285 genes more highly expressed in untreated SVEC (P 1.5). These genes represented various atherosclerosis-related pathways including responses to proliferation, oxidoreductase activity, antiinflammatory responses, cell growth, and hemostasis functions. Moreover, stimulation with oxidized LDL induced dramatically greater gene expression responses in CAEC compared with SVEC, relating to adhesion, proliferation, and apoptosis pathways. In contrast, interleukin 1beta and tumor necrosis factor alpha activated similar gene expression responses in both CAEC and SVEC. The differences in functional response and gene expression were further validated by an in vitro proliferation assay and in vivo immunostaining of alphabeta-crystallin protein. Our results strongly suggest that different inherent gene expression programs in arterial versus venous endothelial cells contribute to differences in atherosclerotic disease susceptibility.

Multiple-quantum-well GaInNAs-GaNAs ridge-waveguide laser diodes operating out to 1.4 /spl mu/m

Abstract: In this letter, results from a ridge waveguide laser diode (LD) structure, with three GaInNAs quantum wells (QWs) and GaNAs barriers, are presented. The sample was grown by solid source molecular beam epitaxy with an RF plasma nitrogen source. These devices differ from previously reported GaInNAs QWs LDs that used GaAs as the barrier material. The introduction of nitrogen into the barriers reduces the spectral blue shift caused by post-growth annealing. Long wavelength emission out to 1.405 /spl mu/m was observed. The devices exhibited threshold current densities as low as 1.5 kA/cm/sup 2/, high differential efficiency of 0.67 W/A, and a maximum output power of 350 mW.

Double sided liquid metal micro switch

Abstract: A plurality of Liquid Metal Micro Switches (LIMMS) are mounted on opposite sides of a multi-layer substrate. Vias on the substrate and located within the footprints of the LIMMS serve to make connection with the LIMMS. Traces on the internal layers of the multi-layer substrate are routed around and over each other to arrive at a perimeter surrounding the LIMMS, where they emerge again as vias and are available for interconnection with further circuitry via conventional techniques, such as solder balls, wire bonding, a socket, etc. The multi-layer substrate may also incorporate a ground plane to assist in shielding and the fabrication of any interconnecting transmission lines.

Uniformly Sized Gold Nanoparticles Derived from PS-b-P2VP Block Copolymer Templates for the Controllable Synthesis of Si Nanowires

Abstract: A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires...