W. Van Petegem

Electrothermal simulation and design of integrated circuits

An accurate prediction of the electrothermal behavior of power integrated devices is required to design circuits in an efficient way. An electrothermal simulator (ETS) is a combination of SPICE with finite element code, in a relaxation procedure. It simulates the full electrothermal behavior of integrated circuits. Static and dynamic simulations of typical examples, reveal the value of ETS for high-power applications. Some specific design rules are derived. They are simple formulas, which estimate the temperature (gradients) on chip. They can be used before any CPU-time consuming simulation takes place which allows a more efficient design and prototype phase. >

The use of an advanced reciprocating gait orthosis by paraplegic individuals: a follow-up study

This article describes the results of a follow-up study of 14 paraplegic individuals who were fitted with the ARGO (Advanced Reciprocating Gait Orthosis – STEEPER*) at least 1 year previously. It was found that 85% were still using the apparatus on a regular basis. The general satisfaction of the users was high, although the functional use was limited. Therapeutic reasons appeared to be the main reason for wearing the ARGO. The points that were most appreciated were the psychological and physiological benefits of standing and walking. Discussion with the users who were paraplegic provided valuable information concerning possible technical improvements to the ARGO.

An EMG-based finite state approach for a microcomputer-controlled above-knee prosthesis

A novel self-contained microcomputer-controlled above-knee prosthesis (AKP) has been developed. The knee mechanism is equipped with a magnetic particle brake providing a continuously variable resistive moment. Several sensors measure the contact pressure under the prosthetic foot, the knee angle and EMG-signals from the stump muscles. This information enables the microcomputer to adjust the braking moment automatically depending on gait mode, gait velocity and other locomotion requirements. The control action is based on a finite state representation of the gait cyclus.

Electrothermal simulation of integrated circuits

The electrothermal simulator (ETS) for integrated circuits is presented. It is based on the alternating operation of an electrical and thermal analysis program. The main links between these two simulators are the model cards, as in a normal simulation program with IC emphasis (SPICE) input, but now provided for each circuit component separately. All temperature-dependent parameters are updated between iterations. A static example simulated with ETS shows the importance of such a combined electrothermal simulation. Future developments are also indicated.<<ETX>>

From learning over e-learning to MyLearning

Lifelong learning is the new adagio for modern European citizens preparing our knowledge-based society for the next decades to come. Therefore, we need open and flexible learning systems, enabling individual learning pathways for all citizens, suitable to their needs and interests at all stages of their lives. This paper will address the question how universities should support the individual citizens in their lifelong learning trajectory, by transforming learning into e-learning with the help of modern ICT, and further into a personalized way of learning, MyLearning.

Electrothermal Simulation of Analogue Integrated Circuits With Ets

Nowadays, high-power devices are integrated together with complex digital and high performance analogue circuits on the same chip. Inappropriate design and/or layout cause major problems with maximum temperature and temperature gradients between components. An accurate prediction of the electrothermal interaction is required to design this type of circuits more efficiently (Poulton et al., 1992). A new electrothermal simulation tool, called ETS, has been developed (Van Petegem et al., 1990; Van Petegem, 1993; Van Petegem et al., 1994). It allows static and transient simulations of circuits where electrical behaviour is seriously affected by thermal effects on chip.

Design of an automatic step intention detection system for a hybrid gait orthosis

An algorithm is presented to detect the step intention of paraplegics walking with a hybrid gait orthosis, the Advanced Reciprocating Gait Orthosis (ARGO) in combination with Functional Electrical Stimulation (FES). It is based on the information of four pressure sensors mounted under the feet. A finite state approach is used. The system has been tested by two paraplegics with positive results.

A BIMOS diode matrix for the characterization of static and transient thermal phenomena on silicon

A diode matrix has been designed and processed in SBIMOS technology in order to obtain a better understanding on the static temperature distributions and transient thermal phenomena in the silicon. The diode matrix is shown to be the perfect tool for determining thermal constants and temperature distributions on chip. This information can be used to evaluate the electro-thermal simulator and to provide designers with more practical information in designing temperature critical ICs, resulting in smaller power ICs for the same performance. Temperature-related problems on chip such as offset voltage due to temperature gradients and maximum allowable temperature can be adequately modeled and hence calculated.<<ETX>>

Voltage versus current driven high frequency EIT systems

A voltage driven EIT system is discussed capable of imaging at high voltage frequencies. This system makes no use of current sources to inject the current and no common mode feedback is implemented. However, experiments have shown that the sampled data compared to simulated data does not show a large systematic error (less than 2% for 12 bit ADCs).

Electrical impedance tomography systems based on voltage drive

At the ESAT-MICAS research facility in Leuven, several EIT systems have been designed and realised. The latest hardware set-up makes use of a PC to control the data collection and to reconstruct the images. A voltage drive strategy and no common-mode feedback are some of its specific characteristics. The function-generator produces signals with a frequency between 10 and 100 kHz, so multifrequency images can also be produced. Static images have already been obtained and (semi-)real time imaging is possible with our latest mark IV system. This system has 16 bit analogue-to-digital convertors and is capable of taking 50 x 10(3) samples/s.