Alexios D. Spyronasios

Wavelet Analysis for the Detection of Parametric and Catastrophic Faults in Mixed-Signal Circuits

Methods for testing both parametric and catastrophic faults in analog and mixed-signal circuits are presented. They are based on the wavelet transform (WT) of the measured signal, be it supply current (IPS) or output voltage (VOUT) waveform. The tolerance limit, which affects fault detectability, for the good or reference circuit is set by statistical processing data obtained from a set of fault-free circuits. In the wavelet analysis, two test metrics, one based on a discrimination factor using normalized Euclidean distances and the other utilizing Mahalanobis distances, are introduced. Both metrics rely on wavelet energy computation. Simulation results from the application of the proposed test methods in testing known analog and mixed-signal circuit benchmarks are given. In addition, experimental results from testing actual circuits and from production line testing of a commercial electronic circuit are presented. These results show the effectiveness of the proposed test methods employing the two test metrics against three other test methods, namely, a test method based on the root-mean-square value of the measured signal, a test method utilizing the harmonic magnitude components of the measured signal spectrum, and a method based on the WT of the measured signal.

Design and development of a versatile testing system for analog and mixed-signal circuits

In this paper the design and development of a test system based on a microcontroller is presented. This system is versatile to test various analog and mixed-signal systems without any hardware modification. Preliminary results from the application of the system to the production line testing of emergency light products are presented showing the effectiveness of the proposed testing scheme.

Circuit Implementation of a Supply Current Spectrum Test Method

A supply current spectrum test method is developed in this work, and its implementation using measurements of various analog circuits is presented. Statistical data from fault-free circuits are effectively exploited to compute tolerance limits that affect fault detectability. A low-cost microcontroller-based measuring system that was designed and utilized for mixed-signal fault detection in production line and used for the application of the proposed method is briefly described. For exploitation of combinations of test methods, time consumption considerations are given to derive conditions under which a test method can effectively be used as a preprocessing step before another more time-consuming test method. Experimental results demonstrating the effectiveness of the proposed supply current test method are presented.

Simulation and measurements for testing an emergency luminaire circuit

In this paper simulation and measurements used for testing an emergency luminaire are presented. Model validation is accomplished by comparing the PSpice data with the experimental data acquired with the help of an oscilloscope and a measuring system which offers real-time storage of current and voltage waveform measurements. Simulations of the fault-free circuit and faulty circuit instances proved to be in good accordance to the measured data. From the simulated fault-free and several commonly encountered faulty circuit cases, a fault dictionary can be built in order to be used in a fault circuit diagnosis method for emergency luminaire circuits.

Power supply current testing in the production line of emergency luminaire circuits

In this paper a test method based on the measurement of the magnitude of the supply current spectrum is presented. The method is evaluated as a preprocessing test step for fast detection of faulty circuits. This method, along with a functional test method are utilized by a versatile system, which is used for production line test of emergency luminaire circuits. Main advantages of the method are the single test point and the single measured signal (power supply current) that are needed. Extensive comparisons were conducted between the functional test results and power supply current measurements acquired from the production line of emergency luminaire circuits showing the effectiveness of the method.

Wavelet analysis of measurements for on-line testing analog & mixed-signal circuits

In this paper a test method based on the wavelet transformation of the measured signal, be it supply current (IPS) or output voltage (VOUT) waveform, is presented. In the wavelet analysis, a test metric named discrimination factor is introduced utilizing information from initial two decomposition levels of the measured signal. The tolerance limit for the good circuit is set by statistical processing data obtained from the fault-free circuit. Experimental comparative results between the proposed method, a test method based on the RMS value of the measured signal, a test method utilizing the harmonic magnitude components of the measured signal spectrum and a method based on the wavelet transformation of the measured signal are presented showing the effectiveness of the proposed testing scheme.

Efficient testing of an optical feedback pixel driver using wavelet analysis

A method for testing an optical feedback pixel driver (OFPD) is presented. It is based on the wavelet transformation of the measured output pixel current (IPIXEL) waveform. In the wavelet analysis, a test metric is introduced which relies on the wavelet energy computation from the trend and detail coefficients of the IPIXEL waveform. The proposed test method is general and may be applied also for testing other analog and mixed-signal circuits. Comparative simulation results are presented between the proposed method and a method utilizing the calculation of the integral of the IPIXEL. The results show a +13.33% improvement in fault coverage by using the proposed testing scheme.

Testing Parametric and Catastrophic Faults in Mixed-Signal Integrated Circuits Using Wavelets

In this paper a test method for testing both parametric and catastrophic faults in analog and mixed signal Integrated Circuits (ICs) is presented. It is based on the wavelet transformation of the measured signal, be it supply current (IPS) or output voltage (VOUT) waveform. The tolerance limit for the good or reference IC is set by statistical processing data obtained from a set of fault-free ICs. In the wavelet analysis, two test metrics one named discrimination factor and one utilizing Mahalanobis distances are introduced. Both metrics rely on wavelet energy computation. Results from the application of the proposed method in testing known analog and mixed signal IC benchmarks are presented showing the effectiveness of the proposed testing scheme.

Testing an Emergency Luminaire Circuit Using a Fault Dictionary Approach

In this paper a model for emergency luminaire circuits is utilized for building a fault dictionary so as to be used for circuit fault diagnosis. Simulation and measurements used for testing an emergency luminaire were performed in order to verify the emergency luminaire circuits behavior. Simulation results were compared to the experimental data acquired with the help of an oscilloscope and a measuring system, which offers real-time storage of current and voltage waveform measurements. Simulations of the fault-free circuit and faulty circuit instances proved to be in good accordance to the measured data. A fault dictionary is built and is successfully used to diagnose the most commonly encountered faults in the circuit.

Multiple Parametric Circuit Analysis Tool for Detectability Estimation

In this paper a software tool is presented which is capable of producing testability metrics for analog and mixed-signal circuits. These metrics are obtained by performing probabilistic analysis techniques. The presented tool acts as a shell utilizing the power of state of the art external schematic and simulation programs and offers to the user a graphical interface for circuit design and test. This interface is transparent to the user elaborately hiding all the complex task manipulations. Preliminary results are presented showing the effectiveness of the proposed scheme.