Testability analysis for analog circuits provides valuable information for designers and test engineers. Such information includes a number of testable and nontestable elements of a circuit, ambiguity groups, and nodes to be tested. This information is useful for solving the fault diagnosis problem. In order to verify the functionality of analog circuits, a large number of specifications have to be checked. However, checking all circuit specifications can result in prohibitive testing times on expensive automated test equipment. Therefore, the test engineer has to select a finite subset of specifications to be measured. This subset of specifications must result in reducing the test time and guaranteeing that no faulty chips are shipped. This research develops a novel methodology for testability analysis of linear analog circuits based on pole-zero analysis and on pole-zero sensitivity analysis. Based on this methodology, a new interpretation of ambiguity groups is provided relying on the circuit theory. The testability analysis methodology can be employed as a guideline for constructing fault diagnosis equations and for selecting the test nodes. We have also proposed an algorithm for selecting specifications that need to be measured. The element testability concept will be introduced. This concept provides the degree of difficulty in testing circuit elements. The value of the element testability can easily be obtained using the pole sensitivities. Then, specifications which need to be measured can be selected based on this concept. Consequently, the selected measurements can be utilized for reducing the test time without sacrificing the fault coverage and maximizing the information for fault diagnosis.

Spatial light modulators (SLM) have been developed since the 1940s using different fabrication technologies. SLMs can be employed for various applications like projection displays, direct-writing systems for photolithographic processes and optical signal processing. This dissertation gives an overview of the studies on a micromechanical SLM with a deformable oil film as actuator placed on a CMOS-circuit with mirror-layer on top. The oil film deforms due to electrostatic forces at the surface where an electric field is applied. Incident light is transmitted through the deformed oil film and reflected by the mirror layer. The local oil film deformations result in a spatial phase modulation. A simple Schlieren optics can convert the phase modulation into an intensity pattern for image projection. This work presents the first SLM devices with a deformable oil film that is addressed by a CMOS active matrix. This new technology is called moving liquid mirror (MLM). Simulation, design, fabrication and measurements of first devices are described. The devices bear 256x256 pixels of 16um or 20um size. Contrast ratios of 43:1 in the 0th order of diffraction were measured. Gray scaling is possible with analogue voltage levels. Dynamic operation proved the capability of the MLM-actuators to operate at a frame rate of 200Hz. Arbitrary patterns can be loaded into the active-matrix CMOS-circuit with oil film for the projection of intensity images.

This habilitation thesis has to primary goals. First, the often mentioned prejudice against higher order statistics, that a great number of data is necessary for accurate parameter estimation, should be proven. In fact, we show by theoretical analysis of different applications for higher order statistics that this prejudice is not true in general. The main conclusion is that the use of higher order statistics has to be proven case-by-case. The second goal is to present a new concept - so-called modulated cumulants - for identification of linear time invariant system. We show by simulations that these concept leads to very accurate estimates compared to known methods.

The subject of this thesis is the development and the characterization of threedimensional electrode arrays for the electrostimulation of neural cells. For the development of the electrode fabrication process special attention was paid to the compatibility with existing CMOS processes. This allows the fabrication of electrodes and electronic control circuitry on the same substrate in a close distance without the need of further assembly techniques. The fabrication process of the electrode arrays essentially consists of electrodeposition of gold to form the threedimensional electrode structures and a further electrodeposition of iridium in order to improve the electrode characteristics significantly. Cylic voltammetry and impedance measurements were performed to characterize and compare the fabricated iridium electrode arrays with other common electrode materials such as platinum, gold and titanium nitride. It was shown that the iridium electrodes have lower impedances over the considered frequency ranges and higher permissible clamp voltages for electrostimulation. Furthermore a method and a device for scanning potential microscopy was developed. Measurements of the local potential distribution of different electrode configurations and electrode shapes in saline solutions have been performed using this scanning potential microscope. In this way results obtained by finite element simulations have been verified experimentally. It was also shown that the presented method offers a better spatial resolution than previously reported methods.

Today the development of industrial CMOS processes with respect to minimum structure size allows the realisation of CMOS image sensors with a spatial resolution comparable to CCD image sensors. While CCD's still provide images of higher quality, CMOS sensors can take advantage of the possibility of monolithic integration of optical sensor devices with analog and digital signal processing as well as high flexibility with respect to sensor readout. CMOS technology allows the realisation of low-cost single-chip camera electronics with very low power consumption and application specific properties. As a basis for future developments of CMOS imaging systems frequently used concepts for optical sensor devices and sensor readout circuits are analysed with respect to noise, dynamic range, linearity and speed. It is shown, how to optimise sensor circuits with respect to these properties. To demonstrate the advantages of CMOS technology compared with CCD technology, two integrated image sensors are presented. The image rs provide a very high input dynamic range and perform on-chip image processing inspired by the funcionality of the human retina.

In this work the generation of shock-waves and short electrical pulses on nonlinear transmission lines (NLTL) showing transients down to 3.6 ps and amplitudes of 1V - are presented. Special emphasis is layed upon the development of monolithic integration of planar schottky-diodes and coplanar waveguide structures based on InP-semiconductor material. The methods of simulating nonliear propagation effects on NLTL, designing and technology of NLTL and at last the experimental investigations in order to measure the generatred transients both in the time domain and frequency domain are shown in detail.

The non-destructive and contactless current detection is highly required for the function- and failure analysis of integrated circuits (ICs). Up to now, different measurement techniques have been proposed and introduced. No commercial measurement technique has been available for the application. The aim of this work was to develop a scanning current measurement technique, that allows to detect currents on ICs contactless. Micro-miniaturized magneto-resistive (MR) sensors were used for the current detection. The measurement principle is detecting and assessing the magnetic fields over the current carrying conducting line. Based on the MR sensors, a new probe was constructed. This probe enables parallel to the current detection, a topography measurement. Furthermore, different measurement techniques were introduced and successfully applied, for the AC-current detection in µA-range and in MHz-range on the test structures. Finally, the functionality of the scanning current measurement technique was demonstrated by the current detection on a real IC.

Nanocrystal films may be used as detector material in sensors, as charge storage or conducting channels in devices. In this work lead sulphide (PbS) nanocrystals are generated in the gas-phase and deposited onto substrates forming nanocrystal films. A technology is developed for lateral structuring of these films on the substrate and to process them further by microelectronic standard processes. The pattern of the nanocrystal film is scaled down by several hundreds of nanometers compared to the used photoresist mask pattern. The responsible mechanism is found by consideration of physical mechanisms and usage of a trajectory simulation program. For basic electrical investigation a system is designed for production of nanocrystal films and electrical characterization under clean conditions. Noise measurements and I-V characterizations are performed. Both, single charge transport and charge transport through the interface of nanocrystal film and substrate have been found. The volume of the nanocrystal film is for the current transport not important. PbS nanocrystal films can be used in future devices for definition of high resolution current paths. Current designs can be used to downscale the device patterns without applying high resolution lithography. The parallel process technology with optical lithography still can be used to implement the films into microelectronic devices. With the trajectory simulation program the geometry can be predicted. The developed technology and the results can be transmitted to other material systems.

The vertical optical travelling-wave modulator represents a new high-frequency element for optical data processing. The modulator is designed for a wavelength of 1200 nm and combines the layered structure of vertical optical modulators based on pseudomorphic InGaAs/GaAs quantum-wells with microwave lines from the MMIC technology. The quantum confined Stark effect is used to modulate the optical signal. The multiple quantum-well structure is embedded into an asymmetrical Fabry-Perot resonator built from a Bragg reflector and an aluminum layer to increase the electrooptical effect. The modulators produces a reflectivity change of 0,28. Large scale travelling-wave modulators are capable of critical frequencies higher than 40 GHz. By varying the width of the central conductor of the microwave line, the slow-wave factor could be varied experimentally between 4.8 and 12,7. The applied microwave produces a modulation lattice along the microwave line which can be used in a high frequency beam-steering element for optical information processing

The filtration efficiency of fibrous filters shows in the submicron particle regime a bold reduction. The reason for this behavior is the transition from interceptional to diffusional particle capture. Particle size dependent filtration mechanisms cause a minimum in filtration efficiency at particle sizes about 0,2 micrometer. Previous investigations have shown that a reduction of particle penetration, i. e. enhancement of filtration efficiency due to variation of the filterstructure (diameter of fibres, packing density, depth of filterlayer) results in a higher resistance to flow and causes a higher pressure drop. Another way to improve filtration efficiency without changing the filter structure is the use of additional electric particle capture mechanisms. The main advantage is the higher filtration efficiency without increasing the pressure drop. Today electric particle capture mechanisms are mainly applied in electret filters, which consist of electric inhomogeneous charged fibres. However, the fibres of electret filters loose their charge with time and particle loading. The electric field inside the filter layer will be neutralized so that filtration efficiency decreases. To avoid this disadvantage a new type of filter can be used, in which dielectric fibres become polarized by an external electric field. This field maintains an inhomogeneous electric field inside the filter layer. Aim of this thesis is the development of a new filter, which will be optimized for filtration efficiency without increased pressure drop in conjunction with external electric fields. The new filter will be produced with alternating thin translucent conducting layers and filterlayers of dielectric fibres. In that way it will be possible to obtain strong electric fields at low applied voltages inside the filter layers. The applied voltage should be in the range of 220V. The flow direction is perpendicular to the layers and parallel to the direction of the electric field.