Cyber-Physical Systems Design [mt]

2012-04-25, E. Schubert: Zukünftige Cyber-Physical Systems (CPS) sind eine neue Form von Software-intensiven Embedded Systems, die zunehmend untereinander vernetzt sind – immer mehr auch über mobiles Internet - und mittels heterogener Schnittstellen mit der physikalischen, "echten“ Welt interagieren. Die physikalisch reale Welt wird durch CPS nahtlos mit der virtuellen Welt der Informationstechnik zu einem Internet der Dinge, Daten und Dienste verknüpft. Die daraus resultierenden... [mehr]

Closed-loop Inductive Link for a Wirelessly Powered Epi-retinal Implant [mt]

2012-03-12, H. Xu: Functional electrical stimulators have been widely researched as its capability to partially restore functions of the neurologically impaired individuals. For powering up, wireless power transmission through an inductively coupled link is often considered, as no transcutaneous tethering cable or battery replacement is required. Recently, we have demostrated an epi-retinal stimulator frontend that is able to self sense the compliance voltage and the power level that is... [mehr]

Using FPGA to measure bit error rate [rp]

08.12.11, Tianyi Liu: In a standard optical link, laser diode transmits the modulated optical signal. The photodiode received the optical signal and works together with transimpedance amplifier and limiting amplifier for data recovery. The bit error rate or bit error ratio (BER) is the number of bit errors divided by the total number of transferred bits during a studied time interval. In some application, there is a need to measure bit error rate to determine the performance of the optical... [mehr]

Design of low drop-out regulator in 0.18um CMOS with high PSR and low quiescent current [mt]

22.11.11, H. Xu: Low drop-out (LDO) regulators are becoming the key components in power management ICs for nowadays portable devices. As compared to switch mode power supplies, LDO can provide not only a constant output voltage with less power consumption, but also improved noise performance. In this project, a LDO will be designed in XFAB 0.18um CMOS technology for a wirelessly powered multi channel neural recorder. Since in the targeted system, the LDO comes after an AC-DC rectifier and the... [mehr]

Modeling and Design of Integrated Transmission Lines in Sonnet Simulator [mt]

22.11.11, A. Zahabi: Transmission line-based filters have been used recently for high-speed applications in the range of 10GHz. These filters tend to be area-consuming and their specifications is greatly affected by TL quality factor (Q-factor) which is typically lower than 10 due to technology limitations and parasitic effects. Recently, we have focused on modeling and designing of integrated transmission lines (ITLs). The goal is to reduce the occupied area while approaching the highest... [mehr]

Designing a high speed and high sensitivity receiver for optical transcutaneous system [mt]

23.11.11, T. Liu: For the past few decades, there has been a demand for high speed communication between an implanted device and an external device, for example, brain neural recording and visual prosthesis. Compared with other methods like RF or UWB, Optical telemetry system is an excellent choice for this very high data rate transcutaneous communication system. In a standard optical link, VCSEL transmits the modulated optical signal through the skin. The photodiode in the other side of the... [mehr]

High Speed CMOS Current Comparator for Current Based ADCs [mt]

22.11.11, A. El-Kafrawy: Current-mode circuits including current comparators are important building blocks within many analogue circuit designs, particularly for front-end signal processing applications, data converters and increasingly within neuromorphic electronic sys-tems. Also current-mode circuits are natural candidates for image sensory infor-mation processing where current sensing and comparison is necessary.As voltage-mode ADCs already operate at maximum potential and further... [mehr]

Harmonic Distortion Effects of FGBW Compensated Delta Sigma Modulators [mt]

22.11.11, J. Kauffman: Continuous time delta sigma modulators (CTDS) have recently become the key device for broadband wireless and wireline communication. Due to their built in antialiasing filter and the ability to have relaxed sampling requirements, the CTDS modulators are preferred over their discrete time counterparts. In order to design a low power, wide bandwidth CTDS, finite gain bandwidth (FGBW) compensation is used in all integrators in order to lower their power consumption at the... [mehr]

Analysis of Tracking Algorithms for the Parameter Estimation of Sigma-Delta-Modulators [rp]

22.11.11, M. Lorenz: Various circuit non-idealities of continuous-time Sigma-Delta Modulators can drastically reduce the performance of the requested A/D-conversion. Since some of these non-idealities can even occur during run-time, e.g. due to temperature-effects, it is not possible to take account for suppression of those effects already during the design process of the circuit. To restore the original behaviour of the converter, it would be desirable to measure the non-idealities concurrent... [mehr]

Modelling of Non-Linearities in CT Sigma-Delta Modulators for Simulation and Two-Dimensional Transfer Functions [mt]

21.11.2011, T. Brückner: In order to accurately test and evaluate a CT Sigma-Delta modulator design on a high-level basis, the behaviour, as well as non-idealities have to be modelled precisely. One of this non-idealities are non-linear transfer characteristics of devices in the circuits. This non-linearities can be dependent on different factors like the frequency or the amplitude of a processed signal. In case of a CT Sigma-Delta modulator, the non-linearity of the D/A converters in the... [mehr]

A Reference-Free Successive Approximation ADC for a Neural Recording System [mt]

21.11.2011, U. Bihr:  In order to understand the activity of neural cells, their signals can be electrically recorded. These signals typically have small values (50-500μV) with a frequency range between several mHz to 7.5kHz. Several hundreds up to one thousand channels on one chip are necessary to get a good evaluation of the neural activity. The temperature of the brain-tissue must only increase by a few degrees to avoid damages on the brain. Thereby, the requirements with respect to... [mehr]