High gain power switching using field controlled thyristors

A technique for high gain power switching using field controlled thyristors is described. This technique uses a MOSFET connected in series with the FCT to control the current flow. The circuit exhibits normally-off behavior and is capable of operation at high voltages. The current through the FCT can be turned on and off by the application of a low voltage gate signal to the MOSFET. Turn-on and turn-off times of less than 1 μs have been observed at a current gain of over 30. The new gating technique offers the advantage of the large operating current density of the FCT even at high breakdown voltages and the high input impedance of the MOS gate used to trigger the device during power switching.     

Multistage network with globally controlled switching stages and its implementation using optical multi-interconnection modules

Plane-to-plane guided-wave-based interconnection modules are proposed as building blocks for scalable optoelectronic multistage interconnection networks (MINs). This approach leads naturally to a MIN paradigm based not on cascading switching stages containing several size-reduced crossbars, as in the shuffle-exchange (SE) networks, but on cascading permutation-reduced crossbars instead, one per stage. The interest of such an architecture lies in the control simplicity and scalability potential. Transparent circuit switching for permutation routing is possible in such an unbuffered "globally switched" multistage interconnection network (GSMIN). Preliminary experiments using fiber-based interconnection modules are presented. Performance analysis and simulation of a buffered GSMIN is also studied for packet routing purposes.     

Electron-beam metrology and inspection

Production of integrated circuits necessitates pattern inspection and measurement of critical dimensions to guarantee yield and quality. The shrinking of pattern size in microelectronics requires progressive employment of electron-beam techniques for this purpose. GaAs technology and integrated optics pose additional challenges.Critical dimensions, e.g. linewidth and pitch, as well as placement accuracy of patterns on wafers or masks are to be examined. The measurement accuracy of any e-beam technique is influenced by the quality of the instrument but also by the process of signal formation and by charging effects. High- and low-voltage operation are possible, both having a certain range of applications. Low-voltage operation requires the electron optics to be adapted, but minimizes charging and damage. The algorithms of peak detection, threshold and automatic threshold crossing as well as linear regression may be used for detection of the pattern edges.Inspection is necessary to monitor pattern fidelity, and in an automated form it is intended to be utilized for defect detection. Pattern-to-pattern comparison, pattern-to-data comparison, and feature extraction are the techniques which have been investigated so far.     

Electron-beam microcolumn fabrication and testing

In this paper, we report the improvement of a process for full microfabrication of miniaturized electron lenses specially design for low-energy (100 eV) lithography tools. The main advantages of this technique are the following. It is batch processing oriented, meaning that lenses can be easily built in a full wafer fabrication. With this procedure it is possible to develop a completely integrated process for machining arrays of lenses. Lens bores are aligned using an electron lithography process, resulting in highly accurate positioning. Finally, the source lens chip has not only one but several sets of lenses with different aperture-sizes, each producing a different beam diameter. A scheme is proposed with which the appropriate lens can be selected by means of a deflection system.     

Variable-bandwidth filters using switching

It is shown that, if a switching technique is used to scale the bandwidth of a lowpass filter, the resultant circuit has some of the characteristics of an N-path filter. The consequence of this is that the signal frequency must be bandlimited to avoid spurious responses at the switching frequency and its harmonics.     

A fast switching segmented anode NPN controlled LIGBT

An ultrafast low energy loss lateral insulated gate bipolar transistor (LIGBT) with a novel segmented anode structure is demonstrated. The anode comprises segments of p/sup +/ and n/sup +//p (n/sup +/ region formed within a p-type region) along the width of the device. By simply varying the ratio of these segments the tradeoff between conduction and switching losses can be varied. Unlike an anode shorted structure this does not exhibit an undesirable snapback in its on-state characteristics. This structure is simple to realize in a CDMOS process without the need for any additional process steps.     

Two-level switching pattern deadbeat DSP controlled PWM inverter

A two-level switching algorithm of the deadbeat controlled PWM inverter is presented. Two levels, instead of three levels, are used in the pulse pattern. This scheme allows the use of higher switching frequency for a given computation time delay, which results in lower total harmonic distortion (THD) at the output. Control algorithms are derived. The proposed control scheme is implemented using a TI TMS320C14 DSP controlling an inverter to produce a very low THD sinusoidal output voltage. Simulation and experimental results are presented to verify the performance     

Electron-beam fabrication of GaAs low-noise MESFET's using a new trilayer resist technique

A LO/HI/LO resist system has been developed to produce sub-half-micrometer T-shaped cross section metal lines using e-beam lithography. The system provides T-shaped resist cavities with undercut profiles. T-shaped metal lines as narrow as 0.15 µm have been produced. GaAs MESFET's with 0.25-µm T-shaped Ti/Pt/Au gates have also been fabricated on MBE wafers using this resist technique. Measured end-to, end 0.25-µm gate resistance was 80 ω/mm, dc transconductance gmas high as 300 mS/mm was observed. At 18 GHz, a noise figure as low as 1.4 dB with an associated gain of 7.9 dB has also been measured. This is the lowest noise figure ever reported for conventional GaAs MESFET's at this frequency. These superior results are mainly attributed to the high-quality MBE material and the advanced T-gate fabrication technique employing e-beam lithography.     

Software Defined Networking (SDN) controlled all optical switching networks with multi-dimensional switching architecture

Ultrahigh throughout capacity requirement is challenging the current optical switching nodes with the fast development of data center networks. Pbit/s level all optical switching networks need to be deployed soon, which will cause the high complexity of node architecture. How to control the future network and node equipment together will become a new problem. An enhanced Software Defined Networking (eSDN) control architecture is proposed in the paper, which consists of Provider NOX (P-NOX) and Node NOX (N-NOX). With the cooperation of P-NOX and N-NOX, the flexible control of the entire network can be achieved. All optical switching network testbed has been experimentally demonstrated with efficient control of enhanced Software Defined Networking (eSDN). Pbit/s level all optical switching nodes in the testbed are implemented based on multi-dimensional switching architecture, i.e. multi-level and multi-planar. Due to the space and cost limitation, each optical switching node is only equipped with four input line boxes and four output line boxes respectively. Experimental results are given to verify the performance of our proposed control and switching architecture.     

A microprocessor controlled programmable switching module forphased array applications

An Intel 8085 microprocessor-based algorithm is presented to provide programmable switching for p-i-n diodes that can be interfaced with an 8225 programmable peripheral interface chip. This can be useful in the realization of phased array in which p-i-n diode switching modules are to be switched ON/OFF according to a certain desired pattern in the time domain     

On controlled switching of high voltage unloaded transmission lines

The limitation of switching overvoltages on very high voltage transmission lines is traditionally carried out with the aid of circuit breakers — fitted with closing resistors. This widely used system has repeatedly shown itself to be highly efficient. Nevertheless, it is possible to envisage other methods, in particular, those giving control of the circuit breaker instant of closing. This paper examines the possibilities offered by controlled switching on UHV transmission lines and compares existing solutions. It takes into account the various network characteristics that may be encountered. It details the results in terms of overvoltage levels which could be attained, due to the performance of the circuit breaker. The paper also highlights the critical points relative to the application.     

Dynamically controlled channel-to-channel switching in a full-band DS-DBR laser

This paper presents a detailed series of measurements and modeled results that demonstrate rugged switching in a full-band tunable laser between stable, wavelength locked ITU frequencies. During switching a monolithically integrated optical amplifier has been used as a shutter to achieve greater than 40 dB attenuation whilst the wavelength is being tuned. The interactions between the thermal distribution down the laser and the induced frequency deviations are investigated, and the residual frequency deviation of <5 GHz is shown to be predominately thermal.     

A quartz multivibrator using two regenerative switches

A new quartz multivibrator having a 10-ns transition time is described. The frequency dependence on the supply voltage is less than 10^-6per volt. The output voltage is nearly equal to the supply voltage. The circuit can be heavily loaded.     

Electron-beam lithography for small MOSFET's

Electron-beam lithography with a novel multilevel resist structure together with two-dimensional process and device modeling and dry processing with reactive sputter etching have been employed to produce silicon-gate NMOS devices with micrometer and submicrometer channel lengths. Results for transistors and ring oscillators are reported.     

Wavelength switching and routing using absorption and resonance

A resonator side coupled to a pair of waveguides can switch an optical signal between two ports by means of absorption. The absorptive mechanism is used to suppress the resonant power transfer, rather than to promote loss. Thus, the input signal only suffers small attenuation, provided that the mode volumes of the resonators can be made small enough. Multiply-coupled resonators lead to improved crosstalk performance for both the ON and OFF switched states. The performance of such devices are analyzed analytically, and universal switching curves are derived     

Electron-beam annealing of ion-implanted silicon

A scanning-electron-beam zapping system for the annealing of ion-implanted semiconductors is described. Experiments have been conducted on silicon implanted with various doses of arsenic and boron. Results show that for a given beam power full annealing is achieved above a threshold exposure.     

Electron-beam exposure of optical gratings

Because of electron scattering, optimum exposure conditions for optical gratings written with a scanning electron microscope depend on the grating period. Experimentally determined exposure conditions are given for gratings of periods down to 230 nm deposited on both conducting and nonconducting substrates. Optimum exposures are shown to be in good agreement with theoretical predictions, but exposure latitude is less than predictions indicate.     

Electron-beam deflection and registration for information storage

An electron-beam-registering system suitable for use with certain types of magnetic store has been devised. Fabrication techniques are discussed and an improved type of system is proposed which will differentiate between positive and negative directions of travel along the x and y axes.     

Dynamical effects of missed switching in current-mode controlled DC-DC converters

Past investigations on nonlinear phenomena in DC-DC converters assume ideal switching and ignore the practical issue of switching ripples, for which the sampled data models yield piecewise smooth but continuous maps. In this brief, we show that the unavoidable nonidealities in the switching result in discontinuity in the map, which drastically changes the bifurcation structures. We demonstrate these effects experimentally, and develop simple one-dimensional models that account for switching delay and transients, and can predict the bifurcations in such systems with reasonable accuracy. Using the recent developments in bifurcation theory, we derive the limiting conditions for a reliable period-1 operation when these effects are considered.