Abgeschlossene Projekte

IC-based electron spin detection for biomedical and material science applications

J. Anders: Methods based on the electron spin resonance (ESR) effect are amongst the most powerful analytical techniques in medicine as well as in the natural and material sciences because they enable to study the structure, dynamics and spatial distribution of paramagnetic species in a large variety of samples. In this context, the main goal of this project is to improve and/or to enhance ... [more]

Frequency-sensitive High-field ESR using CMOS LC Tank Oscillators

D. Djekic: The main objective of the this project is to develop fully-integrated CMOS detectors for combined amplitude- and frequency-sensitive ESR experiments at B0-field strengths between 1.25 and 3 T in order to improve the state-of-the-art in spin sensitivity by at least one order of magnitude and thereby enable a speed-up of the analysis of mass limited biological samples ... [more]

Integrierte Ausleseelektronik für kombinierte Hochgeschwindigkeits-Raster-Ionenstrom-Mikroskopie und hochauflösende Patch-Clamp Experimente

D. Djekic: Die Möglichkeit zur Bildgebung im Nichtkontaktmodus mit subzellulären Auflösungen machen die Rasterionenstrommikroskopie (engl. „scaning ion coductance microscopy“ (SICM)) zu einem vielversprechenden Verfahren für Untersuchungen im Bereich der Molekularbiologie. Kürzlich eingeführte Neuerungen im Bereich der Probenköpfe in Kombination mit neuen Bildgebungsmodi haben dabei die Auflösung, die Stabilität ... [mehr]

Messung neuronaler Aktivität mit kombinierten, multifunktionalen Mikro NMR Proben und Mikroelektroden

J. Handwerker: Konventionelle fMRT Experimente basieren auf dem BOLD-Effekt, der die Messung neuronaler Aktivität über die korrespondierenden lokalen Suszeptibilitätsveränderungen ermöglicht. Diese werden in der Regel mit Hilfe T2*-gewichteter EPI Sequenzen gemessen, wobei eine zeitliche Auflösung im Bereich von Sekunden und räumliche Auflösungen im Mikroliterbereich erzielt werden. Das beantragte Forschungsprojekt zielt auf die Überwindung dieser Beschränkungen in der zeitlichen und räumlichen Auflösung, um so feinere Details der neurovaskulären Kopplungskaskade untersuchen zu können ... [mehr]

Verteilte CMOS Sensorarrays zur Korrektur gradienteninduzierter Artefakte in der Hochfeld-MRT

J. Handwerker: Moderne Forschungs-Magnetresonanztomographie- (MRT-) Scanner mit sehr hohen statischen Magnetfeldern von mehr als 7 T eröffnen die Möglichkeit zur MR-basierten Bildgebung mit signifikant verbesserten Auflösungen im Vergleich zu konventionellen Systemen mit Feldstärken zwischen 1,5 T und 3 T. Allerdings verhindern oftmals Nichtidealitäten in Form von Verzerrungen in den Gradientenfeldern, also den örtlich veränderlichen Magnetfeldern zur Positionskodierung des MRT-Signals, das Erreichen der theoretisch möglichen Bildqualität ... [mehr]

Object-Based Video Compression for Real World Data

C. Feller: All modern hybrid video codecs utilize spatial and temporal redundancy removal to compress video sequences. In order to reduce the data necesssary to properly describe a certain area of an image, the similarity to a reference image is exploited. This process is one of the central elements of each hybrid video codec and is called prediction. One can expect the enhancements of traditional hybrid 2D video compression to settle in the near future. Therefore new concepts need to be explored ... [more]

State- and Parameter Estimation in Sigma-Delta ADCs by Using Kalman-Filters (SiDeKa)

M. Lorenz: Various circuit nonidealities of continuous-time Sigma-Delta modulators can drastically reduce the performance of the requested A/D-conversion. Since some of these nonidealities can occur due to manufacturing of the chip or even during run-time, e.g., due to temperature-drift, ... [more]

Circuit Design for a Highly Reliable Epi-Retinal Stimulator

K. Sooksood, E. Noorsal, H. Xu: In this project, the power efficient and area-optimized CMOS circuits for a highly reliable epi-retinal stimulator are developed. The goal of this epi-retinal stimulator is a capability of >1000  output channel including active charge balancing, ESD protection, and a flexible stimulation protocol. [more]

High efficiency telemetric link for real-time power management of implanted system

H. Xu: Recent researches have demonstrated the promise of developing implantable prosthetic devices to restore lost motor and sensory functions using neural stimulating method. In such an application, inductive links are commonly used for remote powering of the embedded system, because this method does not require any transcutaneous wires, which may cause infections, or any implanted batteries, which need to be replaced at the end of their lifetime. [ more ]

Systematischer Entwurfsprozess für SD A/D Umsetzer mit Parametrisierbarer Optimierung

T. Brückner: Designing CT SD Modulator Filters needs a good insight into the filter design, control theory and stability issues of SD modulators. Therefore archiving good filter characteristics is depending on the knowledge of the designer and the used techniques. [more]

Electrical modeling of retina

M. Gerhardt: In this project we carry out electrical modeling of the nerve tissue and experimental verification of the simulation results. [more]

Video Coding Efficiency Enhancement by means of a Novel Representation of Video Material

J. Wünschmann: The processing chain of film production, coding, distribution and finally reproduction on the consumer display includes processing steps which suggest modifications. Not only fully animated movies but most of the films contain increasing amounts of animated content (e.g. special effects or non-real characters). Every animation is composed of 3D objects and rendered to be represented in frames. [more]

Robust Audio Decoding for Erroneous Compressed Audio Streams

T. Roll: This project focuses on the improvement of the perceptual quality of erroneous compressed audio streams as well as the efficient implementation of these methods on programmable devices (e.g. FPGAs). [more]

High Speed Continuous-Time Sigma Delta A/D Converters

A. Zahabi: To circumvent the timing-related non-idealities of conventional continuous-time sigma-delta (SD) analog to digital converters (ADCs), semi discrete-time elements like transmission lines (TL) can be used. Up to now, the TL based SD modulators for sampling frequency of several hundred MHz using lengthy off-chip TLs have been successfully designed. [more]

Background Correction in Sigma Delta A/D Converters

P. Witte: There exist plenty of possibilities for the correction of non-idealities in CT SD Modulators, e.g. for coefficient mismatch, excess loop delay, D/A error correction and others. Our research focuses on background calibration and correction of SD A/D converters, which track the system into its optimal operating point in a closed loop procedure. The investigated techniques use either test signal injection or work completely blind on the circuits output signal. [more]

Digital Stimulation Control and Protocol for Flexible Neural Stimulators

E. Noorsal: In this work, the digital control for an arbitrary waveform stimulator is investigated. The goal is to achieve an optimal compromise of high flexibility for the flexibility of the stimulation waveforms on the one hand and a feasible complexity on the other hand. This is achieved by digital distribution and execution of the stimulation waveform data, where the external and internal protocol of data transmission is optimized. [more]

Circuit Design for Safe Electronic-Tissue Interfaces

K. Sooksood: In implantable devices, a major problem for functional electrical stimulation (FES) is the charge imbalance due to imperfections of the stimulator electronics. Blocking capacitors have been used to achieve charge balanced stimulation for a long time, because of capacitor's characteristic - allow AC and block DC. In multi-channel stimulator, however, there's no room for blocking capacitors, and active charge balancing has to be taken into consideration in order to avoid electrolysis. [more]

Wavelet basierte Bildkompression

Ch. Günter: Neuartige Datenratenkontrollverfahren, welche auf Modellen der Entropie- und Quantisierungsverhalten basieren, werden in dieser Arbeit entwickelt. Die Minimierung der Rechenleistung für das wavelet-basierte JPEG2000 Bildformat wird hauptsächlich durch die Entwicklung neuer Algorithmen für die Implementierung in eingebetteten Systemen erreicht. [mehr]

Voll Programmierbare LDPC Dekoder

Ch. Beuschel: Datentransfer über einen verrauschten Kanal führt zu Verzerrung und möglicherweise Veränderung des Dateninhalts. Um Übertragungsfehler zu korrigieren werden fehlerkorrigierende Codes eingesetzt. Wir entwickeln partiell parallele Hardware-Implementierungen für voll programmierbare LDPC Dekoder [mehr]

Broadcast Media Box

Ch. Günter, K. Schmidt, F. Böhm: In Kooperation mit den Firmen trinloc GmbH und ATMEL GmbH wurde eine Entwicklungsplattform für DAB Multimedia Systeme entwickelt. [mehr]