Kleinsignalverhalten von MOS-Feldeffekttransistoren

Übersicht Aus dem physikalischen Verhalten von MOS-Transistoren werden Vierpolgleichungen und Ersatzschaltbilder für ein Transistorsegment abgeleitet, die das Kleinsignalverhalten beschreiben und den Einfluß der Verarmungszone zwischen Kanal und Substrat und den endlichen Ausgangsleitwert des abgeschnürten Transistors mit kurzem Kanal enthalten. Zur Berechnung der Kettenmatrix des Gesamttransistors wird ein einfacher Algorithmus angegeben und durch zwei Näherungslösungen für tiefe und hohe Frequenzen ergänzt. Der Theorie wird ein numerisches Berechnungsbeispiel für einen Transistor mit kurzem Kanal zur Seite gestellt.

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Contents From the physical behaviour of MOS transistors four-terminal equations and equivalent circuit diagrams for a segment of an MOS transistor are derived which include the influence of the reverse biased depletion layer between channel and substrate and the finite output admittance of the short-channel saturated transistor. A simple algorithm is specified which allows calculation of the chain matrix of the overall transistor, and completed by two approximation solutions valid for low and high frequencies, respectively. The theory is illustrated by numerical calculations for a short-channel transistor.

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Verzeichnis der verwendeten Formelzeichen b Kanalbreite - C ₀ flächenbezogene Oxidkapazität - C _ox Oxidkapazität im ohmschen Bereich - C _sp flächenbezogene Kapazität der Verarmungszone - E _y y-Komponente der elektrischen Feldstärke - E _kr kritische Feldstärke - G ₀ maximale NF-Vorwärtssteilheit - i Kanalstrom, Augenblickswert - Kanalstrom, Zeiger - i _G Gatestrom, Augenblickswert - _G Gatestrom, Zeiger - i _p Abschnürstrom, Augenblickswert - I _p Abschnürstrom, stationärer Wert - i _sp Strom über die Verarmungszone, Augenblickswert - _sp Strom über die Verarmungszone, Zeiger - ₁ Eingangsstrom eines Vierpols, Zeiger - ₂ Ausgangsstrom eines Vierpols, Zeiger - j _G Dichte des Gatestroms - j _sp Dichte des Stroms über die Verarmungszone - j _y Dichte des Kanalstroms - l Kanallänge - l Kanallänge des ohmschen Bereichs - n Elektronendichte - N _A Akzeptorendichte - q positive Elementarladung - u(y) Kanalspannung, Augenblickswert - U(y) Kanalspannung, stationärer Wert - U(y) Kanalspannung, Zeiger - u _G effektive Gate-Source-Spannung, Augenblickswert - U_G effektive Gate-Source-Spannung, stationärer Wert - U_G effektive Gate-Source-Spannung, Zeiger - U _i Inversionsspannung - u _ox effektive Oxidspannung, Augenblickswert - U _ox effektive Oxidspannung, stationärer Wert - U_ox effektive Oxidspannung, Zeiger - u _sp Spannung über der Verarmungszone, Augenblickswert - U_sp Spannung über der Verarmungszone, Zeiger - U₁ Eingangsspannung eines Vierpols - U₂ Ausgangsspannung eines Vierpols - v _gr Grenzgeschwindigkeit von Elektronen im Halbleiter - Hl Dielektrizitätskonstante des Halbleiters - effektive Elektronenbeweglichkeit     

Device to establish drying conditions for protective coatings at elevated temperatures

Summary An apparatus has been described for determining the drying time of protective coatings at elevated temperatures, and tests have been made with vinyl ether formulations. The device is essentially a miniature Sanderson drying-time meter constructed in an oven where temperatures up to 260°C. can be maintained. Tolerances were made on the order of 0.015 in. for gear clearances and bearing expansion. A special high-temperature grease is the lubricant. Turntables, which make one revolution every 15 min., permit simultaneous evaluation of three films. Reproducible results have been obtained, and uniform conditions apparently prevail throughout the oven. Coatings are prepared by the spinning disc method, and under controlled conditions the film thickness is approximately 0.15 mil. “Tack-free time” and “dryto-touch time” are determined by the usual method of removing sand from the disc. Discs were stamped from aluminum as well as black iron, and differences in drying times observed. Coatings on black iron dry faster than those on aluminum, and its is presumed that iron plays the role of an oxidation or polymerization catalyst. Presented at fall meeting, American Oil Chemists' Society, Chicago, Ill., Oct. 20–22, 1958.     

Systematic bias in job evaluation and market wages: Implications for the comparable worth debate.

Evaluated the consequences of systematic measurement errors in job evaluation and in wage distributions used as a criterion in the empirical validation of job evaluation. The way reverse regression combined with conventional regression could be used to identify systematic errors under a restrictive set of assumptions was also demonstrated. It was found that bias against female key or benchmark job wages had the generally hypothesized negative impact on predictions for female non-key job wages. However, systematic evaluation bias of female jobs does not necessarily serve to the wage disadvantage of all female jobs. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diesel fuel from thermal decomposition of soybean oil

Soybean oil was thermally decomposed and distilled in air or in nitrogen sparge with standard ASTM distillation apparatus. GC-MS analysis showed that approximately 75% of the products were made up of alkanes, alkenes, aromatics and carboxylic acids with carbon numbers ranging from 4 to more than 20. Fuel properties of the pyrolyzed materials were characterized and compared with those of the parent oil. The pyrolyzates had lower viscosities and higher cetane numbers than the parent vegetable oil. Thermally decomposed soybean oil shows promise as alternative fuel for the direct-injection diesel engine. Presented at the AOCS meeting in New Orleans, LA, in May 1987. Address all correspondence to Marvin O. Bagby, NRRC, ARS/USDA, 1815 N. University St., Peoria, IL 61604. Deceased.     

Microbial and chemical assessment of regions within New Orleans, LA impacted by Hurricane Katrina

The city of New Orleans, LA was severely impacted by flooding and wind damage following landfall of Hurricane Katrina in August 2005. The city's drinking water infrastructure was severely compromised and massive amounts of sediment were redeposited throughout the flooded region. Thousands of homes were water-damaged resulting in the rapid growth of mold. In September and October 2005 a convenience sample of selected homes, tap water, surface water, and sediment within New Orleans was assessed for mold contamination, microbial contamination, and heavy metal concentrations. At selected sites, indoor mold spore concentrations were compared to outdoor concentrations. The purpose of this study was to conduct a baseline environmental assessment in an effort to identify public health threats caused by wind and flood damage. Surface waters contained high concentrations of bacterial indicators whereas no bacteria were detected in tap water, even from taps containing no chlorine residual. Sediment samples contained concentrations of lead and arsenic similarto pre-Katrina concentrations. Outdoor total spore (sp) concentrations ranged from >6500 to 84 713 sp/m(3). Indoor concentrations ranged from 6142 to 735 123 sp/m(3). For the 13 locations with matched indoor/ outdoor samples, the mean indoor/outdoor spore ratio was 4.11 (ranging from 0.27 to >11.44). Inside 5 of the 13 homes, total spore counts/m(3) exceeded 100 000, with measurements in the moldiest home exceeding 700 000 sp/ m(3). In conclusion, surface waters had high concentrations of bacterial contamination but no bacterial indicators were present in tap water. Sediment samples did not have appreciable increases in lead or arsenic. Flooded homes, however, contained substantial concentrations of mold which could present a public health exposure route to individuals repopulating and restoring the City of New Orleans.     

Determining the amount of rumen-protected methionine supplement that corresponds to the optimal levels of methionine in metabolizable protein for maximizing milk protein production and profit on dairy farms

The profitability of feeding rumen-protected Met (RPMet) sources to produce milk protein was estimated using a 2-step procedure: First, the effect of Met in metabolizable protein (MP) on milk protein production was estimated by using a quadratic Box-Cox functional form. Then, using these estimation results, the amounts of RPMet supplement that corresponded to the optimal levels of Met in MP for maximizing milk protein production and profit on dairy farms were determined. The data used in this study were modified from data used to determine the optimal level of Met in MP for lactating cows in the Nutrient Requirements of Dairy Cattle (NRC, 2001). The data used in this study differ from that in the NRC (2001) data in 2 ways. First, because dairy feed generally contains 1.80 to 1.90% Met in MP, this study adjusts the reference production value (RPV) from 2.06 to 1.80 or 1.90%. Consequently, the milk protein production response is also modified to an RPV of 1.80 or 1.90% Met in MP. Second, because this study is especially interested in how much additional Met, beyond the 1.80 or 1.90% already contained in the basal diet, is required to maximize farm profits, the data used are limited to concentrations of Met in MP above 1.80 or 1.90%. This allowed us to calculate any additional cost to farmers based solely on the price of an RPMet supplement and eliminated the need to estimate the dollar value of each gram of Met already contained in the basal diet. Results indicated that the optimal level of Met in MP for maximizing milk protein production was 2.40 and 2.42%, where the RPV was 1.80 and 1.90%, respectively. These optimal levels were almost identical to the recommended level of Met in MP of 2.40% in the NRC (2001). The amounts of RPMet required to increase the percentage of Met in MP from each RPV to 2.40 and 2.42% were 21.6 and 18.5 g/d, respectively. On the other hand, the optimal levels of Met in MP for maximizing profit were 2.32 and 2.34%, respectively. The amounts of RPMet required to increase the percentage of Met in MP from each RPV to 2.32 and 2.34% were 18.7 and 15.6 g/d, respectively. In each case, the additional daily profit per cow was estimated to be $0.38 and $0.29. These additional profit estimates were $0.02 higher than the additional profit estimates for maximizing milk protein production.     

Evaluation of the furosine and homoarginine methods for determining reactive lysine in rumen-undegraded protein

Three samples of soybean meal (SBM), 3 samples of expeller SBM (SoyPlus, West Central Cooperative, Ralston, IA), 5 samples of distillers dried grains with solubles (DDGS), and 5 samples of fish meal were used to evaluate the furosine and homoarginine procedures to estimate reactive Lys in the rumen-undegraded protein fraction (RUP-Lys). One sample each of SBM, expeller SBM, and DDGS were subjected to additional heat treatment in the lab to ensure there was a wide range in reactive RUP-Lys content among the samples. Furosine is a secondary product of the initial stages of the Maillard reaction and can be used to calculate blocked Lys. Homoarginine is formed via the reaction of reactive Lys with O-methylisourea and can be used to calculate the concentration of reactive Lys. In previous experiments, each sample was ruminally incubated in situ for 16 h, and standardized RUP-Lys digestibility of the samples was determined in cecectomized roosters. All rumen-undegraded residue (RUR) samples were analyzed for furosine and Lys; however, only 9 of the 16 samples contained furosine, and only the 4 unheated DDGS samples contained appreciable amounts of furosine. Blocked RUP-Lys was calculated from the furosine and Lys concentrations of the RUR. Both the intact feed and RUR samples were evaluated using the homoarginine method. All samples were incubated with an O-methylisourea/BaOH solution for 72 h and analyzed for Lys and homoarginine concentrations. Reactive Lys concentrations of the intact feeds and RUR were calculated. Results of the experiment indicate that blocked RUP-Lys determined via the furosine method was negatively correlated with standardized RUP-Lys digestibility, and reactive RUP-Lys determined via the guanidination method was positively correlated with standardized RUP-Lys digestibility. Reactive Lys concentrations of the intact samples were also highly correlated with RUP-Lys digestibility. In conclusion, the furosine assay is useful in predicting RUP-Lys digestibility of DDGS samples, and the guanidination procedure can be used to predict RUP-Lys digestibility of SBM, expeller SBM, DDGS, and fish meal samples.