Surface acoustic wave (SAW) devices using embedded interdigital transducers (IDTs) on an AlN/diamond/Si layered substrate are fabricated, and their performances are investigated. The Sezawa mode is the dominant resonance with the highest resonant frequency up to 17.7 GHz, a signal amplitude of 20 dB, and an electromechanical coupling coefficient of 0.92%. Comparing these SAW devices with those having the conventional IDTs on the same layered structure, the output SAW power and resonant frequency of devices are improved by 10.7% and 1.1%, respectively, for the embedded IDT devices. This is because the different field distribution leads to the different Bragg reflection and phase velocity for the two types of IDTs. The radiation frequency characteristics indicate that the advantages of the embedded IDTs would be useful for high frequency, high power applications such as monolithic integrated millimeter-wave integrated circuit and high speed communications.

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Perovskite Ba 0.5 Sr 0.5 TiO 3 (BST) thin films with a thickness of 300 nm are deposited on high resistivity silicon through pulsed laser deposition. The permittivity of BST is changed by applying an external electrostatic field. Coplanar waveguides (CPWs) are designed to extract the fielddependent permittivity of the film in the frequency range from 1 GHz to 110 GHz. A Subregional Match 3-Dimensional finite element method (SM 3D FEM) is proposed to implement the permittivity extraction. We analysis the electric field distribution in BST film, and thus divide the BST film in a reasonable way in order to achieve the permittivity of each small region in BST film by S-parameters-phase matching. The relative difference between measured and simulated S-parameters-phase is defined to describe the precision of the result. Experimental results show that the relative difference is less than 1.3%. We also found that the permittivity tunability is almost unchanged in a wide frequency domain, the variation of the tunability less than 0.16. The relative dielectric permittivity ξ BST at 0 V equals 1148.9 at 1 GHz and reduces to 311.7 at 110 GHz, and ξ BST at 100 GHz equals 315.8 at 0 V and declines to 193.4 at 30 V. The tunability of BST film is about 38.7% at 100 GHz.

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Ultrasonic transcutaneous energy transfer (UTET) may be a preferable technology due to its power transfer efficiency, compactness and electromagnetic immunity. A novel wireless UTET scheme is proposed based on phased array technology to improve the transferring efficiency. A finite element method (COMSOL Multiphysics) is applied to investigate the properties of the phased array UTET for optimized design. The effects of transducer element number and designed focusing depth were studied on the acoustic field and the receiving transducer's voltage amplitude.

Abstract:The combination of multi-core, SIMD and VLIW schemes is becoming prevailing in today's media processor architectures. To achieve a deep insight into this trend, we propose a power conscious performance model based on the rationale of Hill and Marty's model. Several representative media application kernels are evaluated on the proposed model. The evaluation result shows that: for none communication applications, a large number of small cores achieve optimal performance; for communication applications, architectures with reduced core count and increased core size is preferred. Meanwhile, by increasing the SIMD width, better power efficiency can be achieved for both types of applications at a small loss of performance.