Mihai Daraban

Forbidden switching patterns to mitigate crosstalk on parallel data buses — CODEC design

Instead of applying physical techniques to prevent crosstalk on off-chip parallel data buses, another approach is to code the sent information, [1]. Through developing of a crosstalk avoidance code (CAC) is possible to create a forbidden transition channel (FTC) that prevents transitions responsible for generating crosstalk, [2]. Rules used in developing a CAC can be very complex, and because of that in some papers is explained only the coding algorithm without given a description of the coder/decoder (CODEC). Some of the CAC presented in literature can have only a theoretical point of view, the physical implementation raising problems regarding the real time execution requirements of such a system [3]. In section IV of the paper is explained how the proposed CAC in [4] can be extended to code a larger bus structure and implement the CODEC. In order to compare the proposed CAC performances, were implemented other two algorithms that try to mitigate crosstalk effects ([1] and [2]). In the paper are presented not only SPICE results, but also measured results obtained on a physical off-chip parallel data bus test setup.

Analyzing crosstalk effects on a parallel bus using eye diagram

Eye diagram it is used in a lot of radio and telecommunication application, but it can also be used in digital signal integrity. This kind of analysis is a common indicator of performance in digital transmission systems. A crosstalk analysis using eye diagram it can be elusive, since it may involve other signals than the desired one. Also because of the way the eye diagram it is constructed it is very hard to determine the bit-stream pattern that determined the collapse of the eye diagram and increased jitter. The purpose is to show that the eye diagram can be used in analyzing crosstalk problems which appears on a parallel communication bus implemented on PCBs, by using SPICE simulator and MatLab code implementation. Based on statistics generated using eye diagram, there can be created algorithms or codes to ensure an error free transmission on a parallel high-speed link, but this belongs to another study.

Mathematical analysis to control power transfer in resonant power converters

This paper aims to present a mathematical analysis method for resonant power converter, in order to control the transfer of power which is transmitted to the load. Starting from the idea that most switching power converters are using the pulse width modulation (PWM) technique to control the switching elements, the paper presents an analysis of the control method that can be applied on such converters and a mathematical analysis of the resonant load that can be found at the output of the circuit. On the other hand, the paper proposes an interactive interface to design and simulate a resonant power converter. The tool can be used by experienced engineers in power converters domain, to properly configure such a circuit, but also by those who are starting to learn and understand how these circuits are working. The tool allows seeing, not just the final values for the components that make the circuit, but also the waveforms form the main components. By doing so, the converters area of operation can be observed, allowing to adjust the design in order to improve the design.

Bus encoding algorithm to reduce crosstalk effects

Usually crosstalk problems are resolved by using physical methods like, guard tracing or increasing the distance between adjacent traces, [1]. Even if these methods yield good results, the bus surface is increased on the printed circuit board (PCB). A solution to this problem is to encode the sent information. By using crosstalk avoidance codes (CAC), there can be resolved crosstalk and inter-symbol interference (ISI) problems. CAC are developed by imposing rules regarding which switching pattern can be sent via the parallel data bus. By doing so, there are created forbidden transition channels (FTC). The purpose of the CAC is to enable a high speed transmission on a PCB built by using mainstream technologies without the high speed manufacturing processes.

Capacitive discontinuity in cross talk effect

There are a lot of studies that show the effect of coupled lines, but most implementation in MatLab are based on using an n-section lump circuit approximation model, which has a limited bandwidth. Also on every PCB, on a trace it appears a capacitive discontinuity, that influences the coupling of the transmission lines. We propose another approach to describe the coupled lines, and which will be capable to determine the effect of capacitive discontinuity on the coupled lines.

The influence of capacitive discontinuity in signal integrity on PCB traces

There are studies which show the effect of capacitive discontinuity on the integrity of a signal transmitted in a trace on a PCB. This kind of discontinuity that can appear in path of the signal to the load are inevitable, because a trace it has at least two corners, sometimes two vias, an occasionally a width change. The presence of this capacitive discontinuity can be treated as a lump capacitor that appears in the path of the signal. We tried to find out where to place via or to make a corner on a trace so the signal would be less affected by this kind of discontinuity.

Software instrument for testing cluster devices using high-speed CAN protocol

This paper aims to present a new method for automated testing of industrial equipment, used primarily in the automotive field. The underlying concept of this work consists in developing an application to test the equipment (DUT — device under test) that automated tests need to be performed on, from the point of view of the hardware system, and in terms of the software loaded on such a device. The developed application also aims to function both as a concept HiL (Hardware in the Loop), and as a SiL (Software in the Loop), providing at the end of the testing routine, the test reports on the method, and tests that the equipment has passed. The application allows monitoring and controlling, in real time, tested devices, using a communication protocol — high speed CAN. Real-time monitoring is done both by the high-speed CAN protocol, for debugging the application, and through video capture, allowing users to perform tests both in testing laboratories and in special laboratories, such as EMC or climatic chambers, where the presence of a test engineer is, many times, restricted.

XpertTrack: Precision Autonomous Measuring Device Developed for Real Time Shipments Tracker

This paper proposes a software and hardware solution for real time condition monitoring applications. The proposed device, called XpertTrack, exchanges data through the GPRS protocol over a GSM network and monitories temperature and vibrations of critical merchandise during commercial shipments anywhere on the globe. Another feature of this real time tracker is to provide GPS and GSM positioning with a precision of 10 m or less. In order to interpret the condition of the merchandise, the data acquisition, analysis and visualization are done with 0.1 °C accuracy for the temperature sensor, and 10 levels of shock sensitivity for the acceleration sensor. In addition to this, the architecture allows increasing the number and the types of sensors, so that companies can use this flexible solution to monitor a large percentage of their fleet.

An educational tool to analyze the electromagnetic radiation

In this paper an educational tool, for helping students in understanding electric and magnetic field radiation is presented. The educational tool is capable to represents in a 3D environment the electric and magnetic radiations from a short current element or a small loop of current. Through this tool, the students will be able to observe the impact that different physical and electrical proprieties, which characterize the two circuit elements, have on the electromagnetic radiation components in near and far field region. The tool will allow a complete analysis, without resorting to simplified mathematical equations, which describe the electric and magnetic field components that radiate from the two electric circuit elements. By doing so, the region of transition between near and far field can also be analyzed properly.

A SPICE analysis on how PDNs can benefit from Crosstalk Avoidance Code

In order to improve Signal Integrity (SI) in parallel data busses physical techniques are used. However, the physical techniques have the disadvantage that affect the component placing resulting in an increase of the Printed Circuit Board (PCB) size. A solution is to code the sent information, so that a Forbidden Transition Channel (FTC) is created, [1]. When it comes to parallel data transmission, not only a SI-analysis, but Power Integrity (PI) analysis is also important. Through such a PI-analysis is possible to determine the voltage fluctuations that might appear because of the switching patterns of the drivers given by the Integrated Circuit (IC) power demands [3]. In the following paper, a SI/PI-analysis is done to determine if by coding the information prevents high voltage ripple on the voltage rail.