GaAs pHEMT-based technology for microwave applications in a volume MMIC production environment on 150-mm wafers

The establishment of a 150-mm (6-in) gallium arsenide (GaAs) facility is described together with the development of very high yielding and cost-effective semiconductor device technologies and a manufacturing capacity of over 40000 wafers/annum. The background to the demand for very high volumes of RF products for this market is discussed, together with the prospects for future growth. The paper describes recent process development by the utilization of a data-driven yield management system to support the delivery of high-quality RF products to customers. Finally, "end of line" DC and RF testing of finished 150-mm GaAs pHEMT foundry wafers is described, enabling scalar measurements of power, noise, and intermodulation products as well as vector measurements of S-parameters and noise parameters at frequencies of up to 40 GHz.     

Earing in cup drawing face-centered cubic single crystals and polycrystals

A simple model of flange behavior during cup drawing was used to predict the earing profile of deep-drawn cups. The relationship between yield surface shape and earing tendency was established, with plane stress yielding corresponding to no hold-down pressure on the flange and plane strain corresponding to no thickening. Using the Schmid law, the earing model was applied to the case of a single crystal in cube position and compared to Tucker’s well-known results.^[6] For the plane strain case, good agreement was obtained with the experiment; but for plane stress, the predicted profile did not agree with the experimental one. Using the Taylor/ Bishop and Hill (TBH) theory^[8,9] and measured crystallite orientation distribution functions (CODF), the model was applied to the case of high-purity aluminum sheet with various cold-rolling reductions (35, 60, 80, and 90 pct). The major experimental trends were again correctly predicted by the plane strain case.     

A diagonalized multilevel fast multipole method with spherical harmonics expansion of the k-space Integrals

Diagonalization of the fast multipole method (FMM) for the Helmholtz equation is usually achieved by expanding the multipole representation in propagating plane waves. The resulting k-space integral over the Ewald sphere is numerically evaluated. Storing the k-space quadrature samples of the method of moments (MoM) basis functions constitutes a large portion of the overall memory requirements of the resulting algorithm for solving the integral equations of scattering and radiation problems. In this paper, it is proposed to expand the k-space representation of the basis functions by spherical harmonics in order to reduce the sampling redundancy introduced by numerical quadrature rules. Aggregations, plane wave translations, and disaggregations in the realized multilevel fast multipole method (MLFMM) are carried out using the k-space samples of a numerical quadrature rule. However, the incoming plane waves on the finest MLFMM level are expanded in spherical harmonics again. Thus, due to the orthonormality of spherical harmonics, the testing integrals for the individual testing functions are simplified into series over products of spherical harmonics expansion coefficients. Overall, the resulting MLFMM can save a considerable amount of memory without compromising accuracy and numerical speed.     

Comparison between the effects of positive noncatastrophic HBM ESDstress in n-channel and p-channel power MOSFETs

The effect of noncatastrophic positive human body model (HBM) electrostatic discharge (ESD) stress on n-channel power MOSFETs is radically different from that on p-channel MOSFETs. In n-channel transistors, the stress causes negative shifts of the current-voltage characteristics indicative of positive charge trapping in the gate oxide. In p-channel transistors, the stress increases the drain-to-source leakage current, probably due to localized avalanche electron injection from the p-doped drain     

Improved HF modem using convolutional coding

The paper describes the design of a digitally implemented modem for use over HF (2-30 MHz) radio channels. As a completely digital approach offers the prospect of a number of significant improvements, a new digital multifrequency-shift-keying (MFSK) modem has been developed that employs a novel digital processing procedure termed code-assisted bit synchronisation (CABS). Signal detection is achieved via a set of noncoherent correlators, whilst symbol synchronisation and error correction are performed using a soft-decision Viterbi decoder. Practical tests of modem show that it operates effectively under both additive white Gaussian noise and real HF channel conditions     

89-GHz fT room-temperature silicon MOSFETs

The authors report the implementation of deep-submicrometer Si MOSFETs that at room temperature have a unity-current-gain cutoff frequency (f_T) of 89 GHz, for a drain-to-source bias of 1.5 V, a gate-to-source bias of 1 V, a gate oxide thickness of 40 Å, and a channel length of 0.15 μm. The fabrication procedure is mostly conventional, except for the e-beam defined gates. The speed performance is achieved through an intrinsic transit time of only 1.8 ps across the active device region     

Energy efficiency, carbon emissions and economic development in Venezuela

Venezuela's vast natural resource base has largely shaped the nation's economic and energy-use patterns. Major opportunities exist for improving the efficiency of energy use in Venezuela and, consequently, restraining the growth of energy-related carbon emissions. This paper presents a detailed report of one potential development path for Venezuela and estimates the ensuing levels of energy demand and CO₂ emissions associated with pursuing this path through the year 2025. The results indicate that by adopting a development strategy that incorporates structural changes in the economy, fuel-switching measures and improved end-use efficiencies, Venezuela can introduce energy efficiency and carbon restraints as part of its economic development process.     

Influence of series resistance in oxide parameter extraction data from accelerated tests

Accelerated reliability tests on thin oxide capacitors can be affected by series resistance effects at high stress conditions. The purpose of this work is to point out such problems both with measurements and simulations. It is shown that breakdown electric field is overestimated. Due to the resulting nonuniform stress, charge to breakdown density is underestimated if the test structure layout is not accurately designed. In any case the series resistance effects can have an undesirable impact on the reliability evaluation of thin dielectrics.     

Gain equalization by mitigating self-filtering effect in a chain ofcascaded EDFA's for WDM transmissions

A simple method of alternatively using high-inversion and moderate-inversion erbium-doped fiber amplifiers (EDFA's) in an optical amplifier chain is presented to mitigate the self-filtering effect and equalize both signal power and signal-to-noise ratio (SNR) of multiple wavelength channels in wavelength-division multiplexing (WDM) transmission systems. The performance of the compensated system with alternatively used high- and moderate-inversion amplifiers is compared with the uncompensated ones where only moderate- or high-inversion amplifiers are employed. The result shows that the compensated system has a flatter gain profile, a lesser signal power spread, and SNR degradation