Integrated Amplifier Circuits for 60 GHz Broadband Telecommunication

Wide frequency bandwidth has been internationally allocated for unlicensed operation around the oxygen absorption frequency at 60 GHz. A power amplifier and a low noise amplifier are presented as building blocks for a T/R-unit at this frequency. The fabrication technology was a commercially available 0.15 m gallium arsenide (GaAs) process featuring pseudomorphic high electron mobility transistors (PHEMT). Using on-wafer tests, we measured a gain of 13.4 dB and a +17 dBm output compression point for the power amplifier at 60 GHz centre frequency when the MMIC was biased to 3 volts V_dd. At the same frequency, the low noise amplifier exhibited 24 dB of gain with a 3.5 dB noise figure. The AM/AM and AM/PM characteristics of the power amplifier chip were obtained from the large-signal S-parameter measurement data. Furthermore, the power amplifier was assembled in a split block package, which had a WR-15 waveguide interface in input and output. The measured results show a 12.5 dB small-signal gain and better than 8 dB return losses in input and output for the packaged power amplifier.     

Analog baseband chain of synthetic aperture radar (SAR) receiver

An analog baseband chain for a synthetic aperture radar receiver implemented in a 130 nm CMOS technology is presented in this paper. Occupying 0.23 mm² of silicon area, the baseband chain consists of a three-stage variable gain amplifier (VGA), a 5th-order gm-C low-pass filter (LPF) and an output buffer. The gain of the chain can be controlled by tuning the control voltages of the VGA and has a range from 25 to 34 dB. 8 dB of the gain is embedded into the LPF. The bandwidth of the LPF is programmable from 100 to 190 MHz by means of capacitor matrices. The chain, which uses a 1.2 V supply voltage, achieves an input-referred noise density of 4 nV/ $ \sqrt {\text{Hz}} $ and an in-band IIP3 of ?46 dBV rms.     

A biosignal instrumentation system using capacitive coupling for power and signal isolation

Requirements for patient safety and a high interference rejection ratio in medical equipment create a demand for effective isolation devices. A system scale approach that uses capacitive coupling for power and signal isolation is presented. In addition, we describe the development of an instrumentation system prototype that applies microwaves for power exchange and bidirectional data transfer across the isolation barrier. The system consists of an isolated transducer unit, a central unit, and a single coaxial cable between the units. The isolation capacitance is as low as 1.6 pF, inclusive of the digital data transfer and power exchange up to 600 mW of isolated direct current (dc) power. The system is suitable for line-powered biopotential measurements and it is shown that reducing the isolation capacitance from 180 to 1.6 pF improves the power line rejection by 30 dB in a typical electrocardiogram (ECG) measurement setup.     

Isolation and HPLC determination of amines in wine

Summary The isolation of the amines from wines for liquid chromatography was accomplished by either continuous extraction with Freon 11-methylene chloride or with butanol-methylene chloride. The former method gives high recoveries for high-molecular weight amines and the latter for low molecular weight amines. Amines were dansylated and detected with fluorescence and UV detectors. The methods were used to determine amine contents of wines from different countries. The identification of amines was based on UV spectra of dansylamides with a diode array detector.Molecular-connectivity indices, , to sixth order were correlated with the liquid-chromatographic retention parameters of the dansyl derivatives of the amines studied. Some amines containing oxygen had to be omitted before high correlations were obtained. The molecular-connectivity index method for predicting the structure of a given amine requires that the unknown amine is of the type studied in the present series.

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Isolierung und HPLC-Bestimmung der Amine in Wein

Zusammenfassung Isolierung der Amine aus Wein für die Flüssigchromatographie wurde entweder durch kontinuierliche Extraktion mit Freon-11-Methylenchlorid oder durch Extraktion mit Butanol-Methylenchlorid durchgeführt. Die erste Methode gibt gute Ausbeuten für die höhermolekularen, die zweite für die niedermolekularen Amine. Die Amine wurden dansyliert und mit Fluorescenz- und UV-Detektoren nachgewiesen. Die Methoden wurden zur Bestimmung der Amingehalte in Weinen unterschiedlichen Ursprungs verwendet. Zur Identifizierung der Amine aus Weinproben dienten die mit einem Diodenreihendetektor aufgezeichneten UV-Spektraen der Dansylamide.Die molekularen Konnektivitätsindexe, , der sechsten Ordnung wurden mit den flüssigchromatographischen Retentionsparametern der Dansylderivate der untersuchten Amine korreliert. Um hohe Korrelationen zu erreichen, muten einige sauerstoffhaltige Amine unberücksichtigt bleiben. Um die Struktur eines Amins mit Hilfe des molekularen Konnektivitätsindexes vorauszusagen, wird vorausgesetzt, daß das unbekannte Amin von dem untersuchten Typ in der vorliegenden Reihe ist.

     

Density-functional tight-binding for beginners

This article is a pedagogical introduction to density-functional tight-binding (DFTB) method. We derive it from the density-functional theory, give the details behind the tight-binding formalism, and give practical recipes for parametrization: how to calculate pseudo-atomic orbitals and matrix elements, and especially how to systematically fit the short-range repulsions. Our scope is neither to provide a historical review nor to make performance comparisons, but to give beginner’s guide for this approximate, but in many ways invaluable, electronic structure simulation method—now freely available as an open-source software package, hotbit.     

Steady-state modelling of extrusion cooking employing response surface methodology

Extrusion cooking has been approached from the point of view of continuous screw reactor technology, applying a heuristic hypothesis to changes in biopolymer aggregate states. Engineering design variables, the nature of basic biopolymer reactions, mass-machine interactions, and problems in the modelling of product quality in extrusion cooking are discussed. Response surface methodology (RSM) and its applications are discussed in detail including its significance and limitations in the study of complicated experimental situations.     

On the implicit integration of rate‐dependent inelastic constitutive models

Although there are many different algorithms for the integration of inelastic constitutive models, the fully implicit backward Euler method has become the most popular one. In this study further investigations on the accuracy of the backward Euler method have been carried out. Also the performance of the discontinuous Galerkin family and some implicit Runge–Kutta time integrators is evaluated. By using a simple scalar model problem accuracy of some integrators is studied when a single finite time step is applied. Conclusions drawn from this scalar model problem has been verified to apply also to a full six‐dimensional strain space formulation by numerical means. Special emphasis is placed on rate‐dependent inelastic creep models. Copyright © 2005 John Wiley & Sons, Ltd.