A new common-emitter hybrid-π small-signal equivalent circuitfor bipolar transistors with significant neutral base recombination

The linear superposition approach to the modeling of small-signal parameters in the presence of substantial base recombination, which involves a virtual transistor without base recombination, is identified to cause incorrect emitter current modeling. All of the terminal current changes can be correctly modeled by using the measured forced-V_BE Early voltage in a new equivalent circuit, which properly accounts for NBR and Early effect in a physically consistent manner. As a result, practical situations of small collector-base resistance (τ _μ) can be properly handled, τ_μ is related to the ac current-drive and ac voltage-drive Early voltages, which facilitates parameter extraction and circuit modeling. Measurements on state-of-the-art UHV/CVD SiGe HBT's show that the conventional assumption that τ_μ is far larger than the forced-V_BE output resistance τ₀ does not apply to devices with significant NBR. In practice, τ_μ can be comparable to (and smaller than) τ₀ depending on the device processing, profiles and operating temperature. Temperature dependent data are presented, and circuit implications are discussed based on the new equivalent circuit     

Reconfigurable RFICs in Si-based technologies for a compact intelligent RF front-end

This paper presents reconfigurable RF integrated circuits (ICs) for a compact implementation of an intelligent RF front-end for multiband and multistandard applications. Reconfigurability has been addressed at each level starting from the basic elements to the RF blocks and the overall front-end architecture. An active resistor tunable from 400 to 1600 /spl Omega/ up to 10 GHz has been designed and an equivalent model has been extracted. A fully tunable active inductor using a tunable feedback resistor has been proposed that provides inductances between 0.1-15 nH with Q>50 in the C-band. To demonstrate reconfigurability at the block level, voltage-controlled oscillators with very wide tuning ranges have been implemented in the C-band using the proposed active inductor, as well as using a switched-spiral resonator with capacitive tuning. The ICs have been implemented using 0.18-/spl mu/m Si-CMOS and 0.18-/spl mu/m SiGe-BiCMOS technologies.     

On Common–Base Avalanche Instabilities in SiGe HBTs

This paper presents a detailed investigation of the key device-level factors that contribute to the bias-dependent features observed in common-base (CB) dc instability characteristics of advanced SiGe HBTs. Parameters that are relevant to CB avalanche instabilities are identified, extracted from measured data, and carefully analyzed to yield improved physical insight, a straightforward estimation methodology, and a practical approach to quantify and compare CB avalanche instabilities. The results presented support our simple theory and show that CB-instability characteristics are strongly correlated with the parasitic base and emitter resistances. The influence of weak quasi-pinch-in effects are shown to contribute additional complexity to the bias dependence of the CB-instability threshold. Measured data from several technology nodes, including next-generation (300-GHz) SiGe HBTs, are presented and compared. Experimental analysis comparing different device geometries and layouts shows that while device size plays an important role in CB avalanche instabilities across bias, these parameters are not sensitive to standard transistor layout variations. However, novel measurements on emitter-ring tetrode transistor structures demonstrate the influence of perimeter-to-area ratio on CB stability and highlight opportunities for novel transistor layouts to increase .     

故障电流磁限制器的设计和构造

按永久磁铁设计制成的故障电流限制器,性能是靠含有硬磁材料的磁滞模型的2维→时间分级→有限元件方法获得的.     

Fatty acids and sterols in oils from canola screenings

One sample of canola seed (variety Tower) and five samples of screenings were commercially processed to yield first an “expeller oil” and subsequently an “extractor oil” by the hexane extraction of the residue. The screening samples contained 25–50% intact or broken canola seed. The balance included 21–31% weed seeds (especially lambsquarter and stinkweed), hulls, fragments of the embryo, and chaff. All the oil samples were analyzed for sterol and fatty acid composition. The extractor screening samples had slightly higher sterol contents than the corresponding expeller samples, while the Tower samples gave the lowest values. The averages (in mg/g oil or extract) for the extractor screening samples were: brassicasterol, 1.0; campesterol, 4.1; and β-sitosterol, 7.3. For expeller screening samples the average were: 0.9, 3.6 and 6.2 and for the Tower oils they were, respectively, 0.9, 3.8, 5.3 and 0.9, 3.5, 4.7. The fatty acid compositions of the screening samples for both extractor and expeller oils were similar to that of the Tower oil except for the higher proportions of docosenoic acid (22:1) and eicosenoic acid (20:1) and the more obvious presence of three C₁₈ conjugated dienes totalling up to 0.6% of one screening oil sample. The docosenoic acid level (mainly erucic acid) ranged from 3.0 to 7.0% for the extractor oils and from 2.5 to 8.0% for the expeller samples, compared to 0.1% for the two Tower oils. The oil contents of the screenings ranged from 20 to 30%, and the fatty acids and sterols appear to be nutritionally useful and innocuous in all respects. Presented in part at the ISF/AOCS World Congress, New York, April–May 1980.     

Sub-30-ps ECL circuit operation at liquid-nitrogen temperatureusing self-aligned epitaxial SiGe-base bipolar transistors

The authors report the operation of emitter coupled logic (ECL) circuits at liquid-nitrogen temperature using self-aligned epitaxial SiGe-base bipolar transistors. A minimum ECL gate delay of 28.1 ps at 84 K was measured; this is essentially unchanged from the room-temperature value of 28.8 ps at 310 K. This delay number was achieved under full logic-swing (500-mV) conditions and represents an improvement of greater than a factor of 2 over the best reported value for 84 K operation. Lower-power ECL circuits have switching speeds as fast as 51 ps at 2.2 mW (112-fJ power-delay product) at 84 K. These results suggest that silicon-based bipolar technology is suitable for very-high-speed applications in cryogenic computer systems     

Half-terahertz operation of SiGe HBTs

This letter presents the first demonstration of a silicon-germanium heterojunction bipolar transistor (SiGe HBT) capable of operation above the one-half terahertz (500 GHz) frequency. An extracted peak unity gain cutoff frequency (f/sub T/) of 510 GHz at 4.5 K was measured for a 0.12/spl times/1.0 /spl mu/m/sup 2/ SiGe HBT (352 GHz at 300 K) at a breakdown voltage BV/sub CEO/ of 1.36 V (1.47 V at 300 K), yielding an f/sub T//spl times/BV/sub CEO/ product of 693.6 GHz-V at 4.5 K (517.4 GHz-V at 300 K).     

Electroless deposited Ni–Re–P, Ni–W–P and Ni–Re–W–P alloys

Coatings of electroless Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys were plated in alkaline citrate baths containing amino alcohols, but not free ammonia ions. The reference Ni–P alloy was used as an intermediate layer in the sandwich: Ni–Me–P/Ni–P/substrate. An extremely homogeneous thickness distribution of all alloy components was found by applying scanning Auger electron spectroscopy (SAES(. The inclusion of refractory metals at the expense of nickel and without substantial change in phosphorus content was established. A non-oxidized state of the codeposited Re and W in Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys was determined by means of X-ray photoelectron spectroscopy examination, as well as by SAES profiles, revealing the absence of oxygen throughout the coatings. All alloy films are amorphous and paramagnetic.     

Transistor noise in SiGe HBT RF technology

This brief presents experimental and modeling results of device noise in SiGe HBT RF technology. By careful bandgap engineering, a simultaneous reduction of RF noise, 1/f noise, and phase noise has been achieved. At a given I_B, transistors with different base bandgap profiles show similar 1/f noise. At a given I_C, however, transistors with a higher β (and hence lower RF noise) show lower 1/f noise. Circuit analysis and simulation shows that the phase noise is reduced as well     

A channel resistance derivative method for effective channel lengthextraction in LDD MOSFETs

A channel resistance derivative method for extracting the electrical effective channel length and series resistance is proposed, and demonstrated on an advanced 0.35 μm LDD CMOS technology. A clear graphic image of the L_EFF and R_SD is obtained directly from the measured channel resistance and its derivative with respect to the gate bias. The method also provides guidelines for the proper gate bias range selection in traditional L_EFF extraction techniques