Dimitris K. Papakostas

A Unified Procedure for Fault Detection of Analog and Mixed-Mode Circuits Using Magnitude and Phase Components of the Power Supply Current Spectrum

A method using the power supply current for fault detection in analog and mixed-mode circuits is presented. A new unified fault detection procedure is introduced, and its fault detection capability is estimated. The procedure combines the rms value and the magnitude and phase components of the power supply current. Certain required discrimination factors are defined, and their values are adjusted to include circuit parameter deviations and matching dependencies for the efficient application of the method. Representative results from the simulation of an operational amplifier (opamp) and a flash analog-to-digital converter circuit are given, showing the effectiveness of the proposed method.

An Improved Optical Feedback Pixel Driver Circuit

An improved optical feedback circuit is proposed with only a few components and a wide range of V data voltages. Its operation is verified by simulation using the HSPICE simulator, PSIA2 thin-film transistor (TFT) model, and our previously published light-impact model of polycrystalline TFTs. In addition, the new optical feedback pixel driver (OFPD) is compared with previously published OFPDs, and its advantages are pointed out and discussed.

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.

Analog fault detectability based on statistical circuit analysis

Statistical multi-parameter circuit simulation is used in this work, in order to estimate the fault detection probability of various analog measurements. Since the method is a simulation-before-test approach, its computational complexity can be considered acceptable utilizing modern computer systems. Parameter deviations and multiple Monte-Carlo analysis are properly handled by a shell program, named MPCAP, which uses the SPICE simulator as a kernel. Theoretical analysis for the calculation of the probabilities is given, along with simulation results from an analog filter example.

Fault detection in linear bipolar ICs: comparative results between power supply current and output voltage measurements

Fault detection in linear bipolar integrated circuits using power supply current measurements is investigated. The most prevalent, catastrophic and parametric faults, have been modelled for the representative (741 type) op amp. The circuit is simulated in both linear and non-linear operations. Comparative results between power supply current and output voltage measurements are given, showing the improvement in fault coverage by the use of the current sensing method.<<ETX>>

Current-Based Testing of Optical Feedback Pixel Driver

A testing scheme of an optical feedback pixel driver is proposed, discussed and simulated by HSPICE. A basic characteristic of the specific circuit is that the gray scales of the pixel are created by pulse width modulation. So, the integral of the output I pixel current (which is proportional to I oled) has to be measured or calculated and used for testing. The testing procedure that is proposed enables the detection and identification of common processing defects up to 96%, as verified from simulation results. Although I pixel current is tend to be very low, the measuring system used, using special instrumentation ICs, is successfully simulated and verified by HSPICE.

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.

Selecting input current waveforms using a hardware testing implementation incorporated in FPGAs

The paper presents the comparison of waveforms for the input stimulus of a circuit under test, using a testing system incorporated in an FPGA, relying on a method based on wavelet transformation of the supply current or load current waveforms. The method differentiates due to the incorporation of different signal inputs according to the needs of the tester and the specifications of the circuit. This is a distinctive and effective method that offers a single-point test measurement solution and may easily be adapted to test various other analog and mixed-signal systems. Experimental results are presented showing the effectiveness of the proposed testing scheme.

Wavelet analysis of current measurements for mixed-signal circuit testing

In this paper a test method based on the wavelet transformation of the measured supply current (Ips) and load current (IL) waveforms is presented. In the wavelet analysis, the test metrics used are utilizing the initial three decomposition levels of the measured signal. Experimental comparative results between the proposed method, a test method based on the RMS value of IPS, a test method utilizing the harmonic magnitude components of the IPS spectrum and a method based on the wavelet transformation of the IPS are presented showing the effectiveness of the proposed testing scheme.