Dan Pitica

Reliability and failure analysis of voting circuits in hardware redundant design

This paper presents some aspects of fault-tolerant design using hardware redundancy. The voter is the key element in N-modular redundant design. Hardware voters are bit voters that compute a majority of n input bits. An m-out-of-n hardware bit voter is a circuit with n bit inputs, and 1 bit output y, such that y=1 if at least m-out-of-n input bits have the value 1. A hardware voter can be implemented with logic gates in CMOS VLSI technology. Designers are looking for optimal designs with respect to the following criteria: circuit complexity, number of logic levels, fan-in and fan-out, power dissipation, testability, or any combinations of the previous requirements in order to obtain high reliability for the voting circuits. A detailed reliability analysis, failure modes and effects analysis of voters at the transistor level, is performed using CARE tools. CARE (computer aided reliability engineering) is a powerful software tool that can be used concurrently in the phases of R&D for complex reliability analysis of electronic circuits. The main goal of these analyses is to identify the best designs of voting circuits, in terms of reliability parameters and to identify the possible technological failures that can affect them.

Accelerated ageing tests for predicting capacitor lifetimes

Being reliability critical components, and widely used in electronics today, electrolytic aluminum capacitors are one of the most likely components to fail under extreme working conditions. Therefore in safety critical applications, their lifetime prediction is of vital importance. The following paper analyses current prediction algorithms and offers an improved solution for capacitor lifetime prediction. The results are obtained from accelerated ageing tests and theoretical data obtained from calculi are compared to real world data obtained from measurements.

The gamification of the study of electronics in dedicated e-learning platforms

This paper presents several examples of implementing the concept of gamification in an e-learning platform specialized in the study of electronics. This concept requires the use of the game mechanics and thinking for non-game applications to actively involve users in solving a problem [1]. It can be implemented in an e-learning platform aimed to motivate the students in continuous learning, to improve the quality of provided information and to promote certain behaviors to be learned by them.

Simulation for power integrity to design a PCB for an optimum cost

One of the biggest design challenges today is to properly design, manufacture, simulate and validate a Power Distribution Network (PDN) in systems with increasing speed, power dissipation and density. PDN are typically comprised of capacitors networks that have several types of capacitors and values to obtain target impedance over the required frequency range for the power/ground planes on PCBs. Capacitors provide a temporary source of localized energy for instantaneous current demands from an IC, and a low-impedance return path for high frequency noise. This paper propose a simulation test for a 4 layer PCB, with power/ground planes, to evaluate the effectiveness and importance of decoupling capacitors, using tools and methodologies to determine the important factors like performance, cost and board area.

Artificial neural network and PID based control system for DC motor drives

This paper presents the design and implementation of a control system for permanent magnet motors using PID and artificial neural network controllers. The system consists of two major components: a PC application and a hardware component controlled by an FPGA device. The role of the system implemented in the FPGA device is to acquire and process data related to the DC motors operation, to control the motors voltage and to exchange data with the PC application. The PC application provides to the user an interface for visualizing information related to the motors operation and for interacting with the system. It implements speed and position controllers based on PID algorithm and artificial neural networks, and provides multiple auto-tuning methods for automatic evaluation of the PID controllers parameters and also training sets for the neural network controller. The main advantage of the system is that it allows to automatically determine the control parameters for different DC motors without any prior knowledge regarding the motor parameters, and to easily verify the performances of the controllers.

Controlling the signal integrity through the geometry of the microstrip on the digital PCBs

The paper is focused on interconnect lines at PCB level and it analyzes the effects of the geometrical parameters of a microstrip upon the integrity of the digital signals that are transmitted over the line. The structure of the trace determines the value of its characteristic impedance which should be matched with the terminations of the line. Due to the non-linear input/output characteristics of the driver/receiver, it is not possible to design an interconnect that will ensure perfect matching during transitions. Therefore a MatLab application was developed to plot the waveforms at the ends of a transmission line based on the driver/receiver V-I characteristics and the characteristic impedance of the trace Z0 - Bergeron method. It must be mentioned that the method was applied for driving signals that have rising/falling times much smaller than the time-delay introduced by the line (TD). Another MatLab application extracts the geometrical parameters of the line (W-width of the track, H-height of the dielectric) from the characteristic impedance and plots the delay introduced by the line and the over/undershoot for the corresponding pairs (W, H).

Behavioral model and a MatLAB simulation interface of vibrating wire transducers

This article wants to reveal a new method to measure and moderate a vibrating wire transducer. Combining a complex measuring procedure that includes data acquisition and a MatLab application, it is possible to calculate the transducers impedance. Furthermore, using higher frequencies (as the resonance frequency), respectively lower frequencies signals, the technique above evaluates correctly some parameters that where previously unavailable and also calculates the impedances real and imaginary parts. The above processes are fully automated under MatLAB platform so the transducers impedance to be efficiently calculated.

Electrical / mechanical / thermal design integration

The Intermediate Data Format (IDF) is a specification designed to provide a neutral representation for exchanging printed circuit assembly (PCA) data among mechanical design (MCAD), PCA layout (ECAD), and physical design analysis (MCAE) applications. Powerful analysis software, like Ansys, Maxwell, Semcad, Altium Designer or SolidWorks - CircuitWorks, can import the idf files and use the model for electromagnetic or thermal analysis. The information can also be used for a mechanical approach.

Analysis of the effect of nonlinear input/output characteristics of digital integrated circuits on signal integrity

The paper studies the reflections of the signals transmitted over PCB traces in the case of nonlinear transmission line terminators. First, the features of the approach presented in (the case of constant terminators) are briefly recapitulated. Next, the improved simulator is presented. This last approach takes into consideration the input/output voltage-current characteristics of the digital circuits. This is necessary because in most of the cases, a nonlinear terminator terminates a transmission line having an input from any one of a plurality of logic types: emitter coupled logic (ECL), transistor logic (TTL), Schottky transistor logic (STTL), low power Schottky transistor transistor logic (LSTTL), complementary MOS (CMOS). Finally, we investigate the signals that appear on the track. Nonlinear elements-in particular, digital integrated circuits having a continuous piecewise-linear voltage-current characteristic-are considered to be the terminations of the line.

Power integrity design tips to minimize the effects of mounting inductance of decoupling capacitors

The simulation and the analysis of a power distribution network (PDN), termed power integrity (PI), are performed in the frequency domain and primarily involve analyzing the power and ground planes and the decoupling capacitors. The capacitors provide a temporary source of localized energy for instantaneous current demands from a IC, and a low-impedance return path for high frequency noise. Capacitors need to be close to the device to perform the decoupling function. Efficient energy transfer from the capacitor to the integrated circuit requires placement of the capacitor at a fraction of a quarter wavelengths of the ICs power pins. The purpose of this paper is to simulate a four layer PCB, with power/ground planes, to evaluate the effectiveness and the importance of decoupling capacitors placement, using tools and methodologies to determine the important factors like performance, cost and board area.