In this paper, various fault location techniques in analog networks are described and compared. The emphasis is on the more recent developments in the subject. Four main approaches for fault location are addressed, examined, and illustrated using simple network examples. In particular, we consider the fault dictionary approach, the parameter identification approach, the fault verification approach, and the approximation approach. Theory and algorithms that are associated with these approaches are reviewed and problems of their practical application are identified. Associated with the fault dictionary approach we consider fault dictionary construction techniques, methods of optimum measurement selection, different fault isolation criteria, and efficient fault simulation techniques. Parameter identification techniques that either utilize linear or nonlinear systems of equations to identify all network elements are examined very thoroughly. Under fault verification techniques we discuss node-fault diagnosis, branch-fault diagnosis, subnetwork testability conditions as well as combinatorial techniques, the failure bound technique, and the network decomposition technique. For the approximation approach we consider probabilistic methods and optimization-based methods. The artificial intelligence technique and the different measures of testability are also considered. The main features of the techniques considered are summarized in a comparative table. An extensive, but not exhaustive, bibliography is provided.

Fault diagnosis of analog circuits

Traditionally, work on analog testing has focused on diagnosing faults in board designs. Recently, with increasing levels of integration, not just diagnosing faults, but distinguishing between faulty and good circuits has become a problem. Analog blocks embedded in digital systems may not easily be separately testable. Consequently, many papers have been recently written proposing techniques to reduce the burden of testing analog and mined-signal circuits. This survey attempts to outline some of this recent work, ranging from tools for simulation-based test set development and optimization to built-in self-test (BIST) circuitry.

A tutorial introduction to research on analog and mixed-signal circuit testing

A DFT (design-for-test) methodology to improve the controllability/observability of internal signals in active filters is presented. The normal filter design becomes an 'analog scan' structure in the test mode. The fundamental theory underlying the proposed methodology is presented, followed by an algorithmic description and the results of several case studies. These results are considered from the perspectives of the overhead incurred and the extension of the technique to other analog structures. The DFT algorithm includes not only the modification technique but also a test generation scheme. The algorithm is suitable for silicon compiler and CAD (computer-aided-design) implementation. Experimental results confirm the validity of the methodology. >

A design-for-test methodology for active analog filters

The d.c. fault dictionary approach has been found very useful for diagnosing hard failures (open circuits and short circuits) in non-linear analogue circuits. In this paper we present the use of several techniques to enhance the capability of the d.c. fault dictionary. These include (1) modelling all non-linearities by piecewise linear characteristics, (2) solving the piecewise linear resistive network by Lemke's complementary pivot algorithm, (3) using multilevel logic operation to compile an integer-code fault dictionary which totally eliminates any post-test calculations. the automatic generation of a fault dictionary for a video amplifier by the use of the computer program HAFDIC is described.

Analogue circuits fault dictionary. New approaches and implementation

The use of alternate tests in addition to specification-based measurements is achieving more recognition in industry due to the higher coverage that they provide. The fault and yield coverages of these tests depend on how the pass/fail test decision is made. In this paper we address the critical issue of accurate test threshold determination for these alternate tests. We propose to post-process the given set of sensitive and linearly independent measurements to synthesize a new set of measurements based on which the pass/fail decision is made. A novel methodology for post processing the measurement results called measurement synthesis is presented. Simulation results show that test effectiveness can be greatly enhanced by measurement synthesis.

Enhancing test effectiveness for analog circuits using synthesized measurements

A theory for the diagnosabilty of nonlinear dc circuits (memoryless systems) is developed. Based on an input-output model, a necessary and sufficient condition for the local diagnosability of the system, which is a rank test on a matrix, is derived. Various ways of reducing the computational complexity of this test are indicated. A sufficient condition for single fault diagnosability, which is much weaker than the necessary and sufficient condition for local diagnosability, is also derived. It is also shown that for diagnosable systems,, it is possible to to pick a finite number of test inputs that are sufficient to diagnose the system. An illustrative example is presented.

http://ieeexplore.ieee.org/iel5/31/23511/01084927.pdf

Diagnosability of nonlinear circuits and systems-Part I: The dc case

A theory for the diagnosability of nonlinear dynamical systems, similar to the one in Part I [1] for memoryless systems, is developed. It is based on an input-output model of the system in a Hilbert space setting. A necessary and sufficient condition for the local diagnosability of the system, which is a rank test on a matrix, is derived. A simple sufficient condition is also derived. It is shown that, for locally diagnosable systems, there exist a finite number of test inputs that are sufficient to diagnose the system. Illustrative examples are presented.

Diagnosability of nonlinear circuits and systems-Part II: Dynamical systems

Based on a discrete-time circuit description, a necessary and sufficient condition is derived for the local diagnosability of the class of dynamical circuits whose branch relations are analytic functions of their arguments. Both the single-fault case and the case where all the parameters are assumed to be faulty are dealt with. The condition is a rank test on a matrix that is determined from a single circuit simulation and sensitivity computation. The technique is illustrated with an example.

V. Visvanathan

Papers

Diagnosability of nonlinear circuits and systems-Part I: The dc case

Diagnosability of nonlinear circuits and systems-Part II: Dynamical systems

A Computational Approach for the Diagnosability of Dynamical Circuits