Harnessing the base-pushout effect for ESD protection in bipolar and BiCMOS technologies

The impact of the base-pushout or Kirk-effect on the ESD characteristic of modern radio frequency (RF) NPN transistors is investigated. Due to the RF NPNs selectively implanted collector the onset of base-pushout is shifted to ESD relevant current levels, expressing itself in a characteristically high-ohmic breakdown mode after first snapback and a non-thermal second snapback, the so-called current mode snapback. Concepts to exploit the base-pushout effect for improved RF protection schemes are presented.     

SCR operation mode of diode strings for ESD protection

Diodes and diode strings in 90 nm and beyond technologies are investigated by measurement and device simulation. After a thorough calibration, the device simulator is utilised to achieve a better understanding and an enhanced device performance of diode strings under static and transient ESD conditions. Thereto, parasitic transistors and a so far neglected parasitic thyristor (SCR) in the diode string are regarded, exploited and optimised.     

Map transformations by optical anamorphic processing

A map transformation is a willful geometrical distortion of an image. Examples are rotation, shearing, and local stretching of the coordinate system. We describe an optical setup that performs a map transformation by spatial filtering with two phase-only filters. The system is able to perform in x- and y-linear distortions (e.g., shears) as well as certain x- and y-nonlinear distortions. The distorting filters introduce no aberrations. The object may radiate coherently, incoherently, or partially coherently. Some experimental results are presented.     

Transient latch-up: experimental analysis and device simulation

A set-up consisting of at least one pulse generator with baseline functionality was used for transient latch-up (TLU) investigations. Dependencies of the TLU sensitivity of test structures on the pulse width and the rise time have been analyzed. Device simulation could reproduce the tendencies and reveals the root cause for the dependencies. In a bipolar product, which is immune against static latch-up, transient latch-up could be triggered, showing clearly the importance of a TLU characterization and the capability of the set-up.     

Wavelength Mismatch Correcting Elements for Volume Holograms Written on a Laser Pattern Generator

Abstract

Holographic optical lenses based on volume gratings commonly suffer from severe aberrations due to wavelength mismatch between recording (blue-sensitive material) and application (often employing diode lasers). Here, methods are described for the precompensation of the aberrations at the recording. Both, aberrations in the phase of the reconstructed wave from the desired wave (‘wave aberration’), as well as aberrations in intensity resulting from deviations from the Bragg condition during reconstruction (‘Bragg aberration’) need to be compensated for. The design method for generating the computer generated holograms is described which are used as precompensating elements in the recording step of the interferometrically produced holographic optical elements. The computer generated holograms are written on a laser pattern generator. Test results of our laser pattern generator are shown to demonstrate its capability for this process. The measurement of the aberrations at the design wavelength in the near infrared is a very important step because it allows to eliminate in a second recording process misadjustment errors which will occur during the first recording step. By modification of at least one of the computer generated holograms the convergence of the procedure can be achieved.     

Über Naturwachse XI: Synthesen und Gas-Chromatographie höherer Cyclohexylparaffine

Natural Waxes XI: Synthesis and Gas Chromatography of Higher Cyclohexyl Paraffins Eight cyclohexyl nonadecanes, 1-cyclopentyl eicosane, and three methyl pentacosanes were prepared by Grignard syntheses to serve as model substances in the investigation of minor components of natural waxes. The retention volumes of the pure substances on three different stationary phases (Apiezon L, SE-30, QF-1) were determined by gas chromatography and their mass and infrared spectra were taken. The effect of the position of substituent on the elution behaviour was studied on a series of cyclohexyl and methyl paraffins. The anomalous behaviour of 2-methyl pentacosan, as reported earlier, was confirmed.     

Die Zusammensetzung der Kohlenwasserstoffe der Kamille (Matricaria chamomilla L.)

The Hydrocarbon Composition of Camomile (Matricaria chamomilla L.) The group separation of camomile (Matricaria chamomilla L.) extracts obtained by petroleum ether is described, By column chromatography hydrocarbons, esters, triglycerides, acetylene compounds, free fatty acids, free fatty alcohols and hydroxyesters were separated in n-alkanes, branched alkanes, several types of monoalkenes, terpenoic hydrocarbons. Single components were identified by means of GLC, GLC-MS, IR-and mas-spectrometry.     

Electromagnetic and structural global model of the TF magnet system in ASDEX Upgrade

The enhancements carried out in the tokamak ASDEX Upgrade (AUG) are oriented toward the preparation of the future physics-related activities of ITER and DEMO. To address the main ITER issues, plasma configurations with a wider operational limit (e.g. higher triangularity) are planned for the future experimental campaigns in AUG. To evaluate the mechanical impact on the toroidal field (TF) magnet system a combined electromagnetic and structural finite element model was set up.At first extensive benchmarks of the models are carried out against the AUG reference design configurations with respect to stress [1], [2], [3], lateral displacement measurements and poloidal flux pattern. The numerical model was then applied to a set of actual high triangularity (HT) configurations generated by a more favorable poloidal field (PF) current distribution made possible by an extension of the power supply system. The resulting change of the poloidal flux pattern and the lateral force distribution has consequences for the coil shear stress and vault stability. Both aspects are monitored by a safety system measuring the PF flux placed on top and bottom of the outer surface of two TF coils (TFCs) between vault and the TFC supporting structure, so called Turn Over Structure (TOS). The range of the new HT configurations has induced a modification of the flux pattern, so that an adaptation of safety system is required to protect the TFCs system. Following the same criteria of the old safety system [4], [5], a new set up of virtual coils will be integrated in the control system of AUG. The motivation of this new set up will be discussed in this paper.