InP D-HBT ICs for 40-Gb/s and higher bitrate lightwave transceivers

The combination of device speed (f/sub T/, f/sub max/ > 150 GHz) and breakdown voltage (V/sub bceo/ > 8 V) makes the double heterojunction bipolar InP-based transistor (D-HBT) an attractive technology to implement the most demanding analog functions of 40-Gb/s transceivers. This is illustrated by the performance of a number of analog circuits realized in an InP D-HBT technology with an 1.2- or 1.6-/spl mu/m-wide emitter finger: a low phase noise push-push voltage-controlled oscillator with -7-dBm output power at 146 GHz, a 40-GHz bandwidth and low-jitter 40-Gb/s limiting amplifier, a lumped 40-Gb/s limiting driver amplifier with 4.5-V/sub pp/ differential output swing, a distributed 40-Gb/s driver amplifier with 6-V/sub pp/ differential output swing, and a number of distributed preamplifiers with up to 1.3-THz gain-bandwidth product.     

Rapid isothermal processing for fabrication of GaAs-basedelectronic devices [HBTs]

The use of rapid isothermal processing (RIP) is detailed for each of the three annealing steps in the fabrication of heterostructure-based devices such as heterojunction bipolar transistors (HBTs). RIP can be used for the alloying of ohmic metal contacts, annealing of ion-bombarded regions for device isolation or parasitic capacitance reduction, and for conventional implant activation annealing. High-speed (f_T=65 GHz) HBTs were achieved using RIP for all of the required heating steps. The authors compare the use of several types of silicon carbide-coated graphite susceptors for eliminating slip formation on 2- and 3-in-diameter GaAs wafers during high-temperature implant activation annealing     

Photodegradation of the carbamate insecticide propoxur

Summary In order to examine the photostability of the insecticide propoxur (2-isopropoxyphenyl-N-methylcarbamate) in the field model experiments with organic solvents were performed. Photodegradation (>280 nm) of propoxur was found to be more efficient in isopropanol solution than in the presence of cyclohexane or cyclohexene. Photolysis in isopropanol and cyclohexane mainly resulted in formation of isopropylphenyl ether. As a trace component 2-isopropoxyphenol was detected. In the presence of cyclohexene on the other hand photomineralisation was found to be the main degradation pathway.

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Photoabbau des Carbamat-Insecticides Propoxur

Zusammenfassung Zur Voruntersuchung der Photostabilität des Insecticides Propoxur (2-Isopropoxyphenyl-N-methylcarbamat) im Freiland wurden Modellexperimente in organischen Lösungsmitteln durchgeführt. Der Photoabbau (>280 nm) von Propoxur verlief in Isopropanol deutlich schneller als in Cyclohexan oder Cyclohexen. Bei Bestrahlung in Isopropanol und Cyclohexan entstand als Hauptprodukt Isopropylphenylether, daneben Spuren von 2-Isopropoxyphenol. Dagegen erfolgte in Cyclohexen der Abbau hauptsächlich über eine Photomineralisierung.

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Dedicated to Professor Dr. H. Niebergall on the occasion of his 65th birthday     

Distilled Collections from Textual Image Queries

We present a distillation algorithm which operates on a large, unstructured, and noisy collection of internet images returned from an online object query. We introduce the notion of a distilled set, which is a clean, coherent, and structured subset of inlier images. In addition, the object of interest is properly segmented out throughout the distilled set. Our approach is unsupervised, built on a novel clustering scheme, and solves the distillation and object segmentation problems simultaneously. In essence, instead of distilling the collection of images, we distill a collection of loosely cutout foreground “shapes”, which may or may not contain the queried object. Our key observation, which motivated our clustering scheme, is that outlier shapes are expected to be random in nature, whereas, inlier shapes, which do tightly enclose the object of interest, tend to be well supported by similar shapes captured in similar views. We analyze the commonalities among candidate foreground segments, without aiming to analyze their semantics, but simply by clustering similar shapes and considering only the most significant clusters representing non‐trivial shapes. We show that when tuned conservatively, our distillation algorithm is able to extract a near perfect subset of true inliers. Furthermore, we show that our technique scales well in the sense that the precision rate remains high, as the collection grows. We demonstrate the utility of our distillation results with a number of interesting graphics applications.     

Mode-locked laser cavities with a single prism for dispersion compensation

We demonstrate the use of a single prism for adjustable dispersion compensation in a mode-locked laser cavity, instead of the standard approach with a prism pair. A simple model based on the prism-pair configuration is presented to determine the group-velocity dispersion by use of ray optics to trace the wavelength-dependent optical axes through the cavity. We experimentally demonstrated this concept with a passively mode-locked diode-pumped Nd:glass laser producing 200-fs pulses with a 200-mW average output power, using only one intracavity prism. The advantages of such a cavity design are simple alignment, reduced loss, and lossless wavelength tunability This technique can be generalized to other angularly dispersive elements such as prismatic output couplers.     

Compact InP-based HBT VCOs with a wide tuning range at W- andD-band

Compact monolithic integrated differential voltage-controlled oscillators (VCOs) operating in W-band were realized using InP-based heterojunction bipolar transistors (HBTs). The oscillators, with a total chip size of 0.6 by 0.35 mm², are based on a balanced Colpitts-type topology with a coplanar transmission-line resonator. By varying the voltage across the base-collector junction of the HBT in the current mirror and by changing the current in the VCO, the oscillation frequency can be tuned between 84 and 106 GHz. At 100 GHz, a differential voltage swing of 400 mV is obtained, which should be sufficient to drive 100 Gb/s digital logic. By combining the balanced outputs of a similar differential VCO in a push-push configuration, a compact source with close to -10 dBm output power and a tuning range between 138 and 150 GHz is obtained     

Selfaligned AlGaAs/GaAs HBT grown by MOMBE

The very low parasitic resistance n-p-n GaAs/AlGaAs heterojunction bipolar transistors (HBT) grown by metal organic molecular beam epitaxy (MOMBE) using all gaseous source dopants are reported. The carbon and tin dopants were introduced through the uses of trimethygallium (TMGa) and tetraethyltin (TESn). To achieve the low parasitics, the graded InGaAs emitter cap layer was doped with tin to 5*10/sup 19/ cm/sup -3/ and the doping level in the subcollector was 3*10/sup 18/ cm/sup -3/. The emitter and collector sheet resistances were 25 Omega / Square Operator and 10 Omega / Square Operator , respectively. The 800 AA thick base layer was carbon doped to a level of 7*10/sup 19/ cm/sup -3/. The base contact resistance and sheet resistance were 0.1 Omega mm and 180 Omega / Square Operator , respectively. With a thin AlGaAs surface passivation layer for the emitter-base junction, the common emitter DC current gain was maintained up to 25, even for 2*5 mu m/sup 2/ emitter size devices. The unity short circuit current gain cutoff frequency f/sub T/, and maximum oscillation frequency f/sub max/, were 48 and 63 GHz, respectively.<>     

Solving multi-criteria problems under risk: an approach explained using the example of rescheduling in dynamic environments

There is a decent number of possible heuristic methods to solve an actual problem in production planning and control. Usually, each solving method leads to a different alternative. In dynamic production environments, decision makers often have to decide between uncertainty and risk. Making multi-criteria decisions under risk is a well-known problem. In this paper, we will consider rescheduling as an example for decision-making in a dynamic production environment. It is used to present an intelligent manufacturing approach for multi-criteria decisions under risk that combines a method for decision-making under risk and a multi-attribute decision-making method. Moreover, for frequently appearing problems, such as rescheduling, a procedure to evaluate the used solving methods is presented. We use this information to achieve a sustainable improvement for the solving procedure of future manufacturing problems.     

An InGaAs-InP HBT differential transimpedance amplifier with 47-GHz bandwidth

Return-to-zero differential phase-shift keying applications require a differential amplifier with high bandwidth, high gain, low noise, and good input impedance match. In this paper, we describe an InGaAs-InP heterostructure bipolar transistor differential transimpedance amplifier with high bandwidth of 47 GHz and high gain of 56 dB-/spl Omega/. The input-referred current noise is less than 35 pA//spl radic/Hz over the measurement range up to 40 GHz.     

The chemical oxygen iodine laser in the presence of a magneticfield. II. Frequency tuning behavior

For pt.I, see ibid., vol.29, no.3, p.933-43 (1993). Results are presented from an experimental/theoretical investigation of the frequency shifting and tuning behavior of a chemical oxygen-iodine laser in the presence of an applied magnetic field. Frequency shifting measurements are presented for both P and S polarization over a range of magnetic field strength from 0 to 3000 G, in a pressure regime (3 torr) where the line shape is Doppler broadened. Theoretical predictions of the location and magnitude of the frequency shifts are shown to be in good agreement with both the present measurements and a previous investigation in the pressure broadened regime