低功耗IC设计流程

引言随着IC设计的集成度和复杂度日益增加,如何进行低功耗设计已成为业界必须面对的棘手问题,而最有效的解决方法之一便是整个行业的有效合作。为此,由应用材料(AppliedMaterials)、ARM(包括其ArtisaARM物理IP项目组)、Cadence和TSMC等公司联合发起的硅设计链产业协作组织(SDC)     

Determination of the Band Offset of GalnP- GaAs and AllnP- GaAs Quantum Wells by Optical Spectroscopy

We report the determination of band offset ratios, using photoluminescence excitation measurements, for GaInP/GaAs and AlInP/GaAs quantum wells grown by gas-source molecular beam epitaxy. To reduce the uncertainty related to the intermixing layer at heterointerfaces, the residual group-V source evacuation time was optimized for abrupt GalnP/GaAs (AlInP/GaAs) interfaces. Based upon thickness and composition values determined by double-crystal x-ray diffraction simulation and cross-sectional transmission electron microscopy, the transition energies of GalnP/GaAs and AlInP/GaAs quantum wells were calculated using a three-band Kane model with varying band-offset ratios. The best fit of measured data to calculated transition energies suggests that the valence-band offset ratio (γ band discontinuity) was 0.63 ± 0.05 for GalnP/GaAs and 0.54 ± 0.05 for AlInP/GaAs heterostructures. This result showed good agreement with photoluminescence data, indicating that the value is independent of temperature.     

High performance pseudomorphic InGaP/InGaAs power HEMTs

Power transistors with a low d.c. supply voltage were demonstrated with pseudomorphic InGaP/In_0.2Ga_0.8As/GaAs heterostructure field effect transistors on GaAs substrates and 1 μm gate length technology. A current density of 200 mA mm⁻¹ and an extrinsic transconductance of 300 mS mm⁻¹ were exhibited on a 400 μm gate width process control monitor device. For a 1 cm gate width device measured at 850 MHz and V_ds = 1.3 V, state-of-the-art results, 57.4% for the PAE, 12.7 dB for the linear gain and 21.5 dBm for the output power, were obtained.     

Stability and functionality of cysteine-less F(0)F1 ATP synthase from Escherichia coli

This case describes a new feature of fetal brain death syndrome, abnormal movements mimicking fetal convulsions being subsequently found to be decerebrate hypertonicity in a brain-dead fetus. It also confirms the diagnostic criteria of fetal brain death, both clinical and ultrasonic. The development of polyhydramnios both prior to and after the presumed neurological event is suggested as an association with the diagnosis of fetal brain death. Increased awareness of this event and the heterogeneity of the presentation may prevent further unnecessary Caesarean sections, as to date only 4 of the 10 cases in the literature were diagnosed prenatally. Utilization of techniques such as fetal blood sampling should be considered to further delineate the diagnosis.     

High-resolution rlectron microscopic investigation of supported platinum particles reduced at high temperatures

High-resolution electron microscopy has been used to characterize the platinum particles supported on TiO₂ or ZnO. After reduction at elevated temperatures, the metallic particles display a regular, faceted shape, and several superstructures, Pt₃ Ti(C), Pt₃ Ti(H), PtTi, and PtZn, have been found. These results, which may involve strong metal-support interaction, have been confirmed by optical diffraction and image simulation.     

On the realization of input-decentralized representations for large-scale systems

The input-decentralization procedure proposed by Siljak and Vukcevic is analyzed in this note. It is shown that the procedure is valid on an open and dense subset of the parameter space of all large-scale systems with controllable subsystems. The examples which have appeared recently for which the proposed procedure fails are isolated points in the entire parameter space.     

Real-time tracing of spermatozoa

A system for improved evaluation of sperm progression is described. Modern andrology laboratories evaluate semen to analyze male ejaculate and to determine male infertility. Many computer assisted sperm analysis (CASA) instruments have been developed to evaluate sperm progression. To overcome the disadvantages of the existing CASA instruments, a real-time spermatozoa tracing system (RSTS) was developed. The RSTS monitors spermatozoa entering a fixed microscope field and traces their paths over a period of time, thus providing kinematic measurements. The RSTS is comprised of a general microscope with imaging equipment, and it enables the user to manipulate the specimen as desired. This article shows how the RSTS differs from conventional CASA instruments and how the proposed system provides an accurate and efficient method for evaluating sperm progression in real time     

Celahinine A, a new sesquiterpene pyridine alkaloid from Celastrus hindsii

A new sesquiterpene pyridine alkaloid, celahinine A [1], and the related known polyester celahin A, as well as the known cytotoxic sesquiterpene pyridine alkaloid emarginatine A [2], were isolated from Celastrus hindsii. The structure of 1 was determined by 2D nmr techniques and was also confirmed by spectral comparison with the related 2.