Fault diagnosis in sequential circuits pdf

Sep, 2007 this article describes an emulationbased method for locating stuckat faults in combinational and synchronous sequential circuits. Sections iii and iv show how this is done for combinational and sequential circuits, respectively. A tracebased method for delay fault diagnosis in synchronous. Diagnostic test generation for transition delay faults using. In this work we describe a diagnostic fault simulator for sequential circuits which evaluates the e ectiveness of a given test set in distinguishing between faults. Pdf on jan 1, 2016, ali abbass zoraghchian and others published a. Basic concept of fault detection and location in sequential. The test sequence generation method described is intended for use with any multilevel, combinational circuit.

A sequential circuit is a combination of combinational circuit and a storage element. Ripple counter increased delay as in ripplecarry adders delay proportional to the number of bits. This paper employs the survey on the fault diagnosis methods in binary digital circuits which can be further optimized for ternary digital circuits. Fault diagnosis in sequential circuits sciencedirect. Binary counters simple design b bits can count from 0 to 2b. Fault diagnosis in sequential circuits 17 with the basic principles involved in the testing of combina tional circuits, such as path sensitizing and the equivalent normal form enf or equivalent sum of products esp 1,2,3. Consequently the output is solely a function of the current inputs. This paper presents a logic diagnosis approach targeting delay faults. Sequential diagnosis procedure can be graphically represented as diagnostic tree.

Error diagnosis of sequential circuits using regionbased. Speci cally, selfcontainedsubsystems, called cones. Delay fault diagnosis in sequential circuits abstract. It is obvious that when we do so, any single fault seeking algorithm would find the second fault candidate a sa0, since now pattern p2 has become a type1 pattern in the modified circuit. Jul 19, 2012 fault diagnosis and faulttolerant control of inputoutput asynchronous sequential machines. It starts with introduction of digital circuit types which are classi ed as combinational circuit and sequential circuit. In fault diagnosis test patterns are applied to the uut step by step.

The considered asynchronous machine is subject to permanent faults, for which the system remains in the faulty condition indefinitely after the occurrence of fault inputs. Faults are detected and diagnosed by applying tests to the inputs of the circuit. Pdf a fault detection method for combinational circuits. Faults are defined and classified, the problems of detection and diagnosis are discussed, and a previously presented algorithm for fault detection is outlined. The modelbased approach is first extended to apply to synchronous sequential circuits. In the algorithm given here, there is also an attempt to manage the complexity of multiplefault diagnosis. For sequential circuits, primary input variables are the known variables. This document is highly rated by students and has been viewed 3464 times.

Autumn 2003 cse370 vi sequentai llogci 1 sequential logic sequential circuits simple circuits with feedback latches edgetriggered flipflops timing methodologies cascading flipflops for proper operation clock skew asynchronous inputs metastability and synchronization basic registers shift registers simple counters hardware description languages and sequential logic. Digital electronics part i combinational and sequential. Fault diagnosis for analog circuits by using eemd, relative. Smith et al fault diagnosis and logic debugging using boolean satisfiability 1607 fig. This implies that a delay fault activated after the application of a test vector.

A fault is defined to have occurred when any circuit variable assumes a value 1, 0, or x which differs from that expected, that. This paper describes an algorithm for the location of faulty components in digital circuits using the modelbased approach to circuit fault diagnosis. Pdf fault modeling of combinational and sequential circuits at. Pdf on improving fault diagnosis for synchronous sequential.

Different types of sequential circuits basics and truth table. Fault detection and test minimization methods for combinational circuits a survey. There are several equivalencies that exist which are useful in fault detection and. Pdf diagnostic fault simulation of sequential circuits.

In the next section, we show how this information may be utilized in order to design fault tolerant circuits. In this paper, we consider the application of fault diagnosis methods for reversible circuits. There are several equivalencies that exist which are useful in fault detection and which make fault location. Fault diagnosis in sequential circuits 19 which distinguishes the most faults which have not yet been distinguished, should be selected first. Efficient sequential modelbased faultlocalization with. The sequential control circuit can be instructed to test any of a number of circuits by executing one of several fixed sequences. In the algorithm given here, there is also an attempt to manage the complexity of multiple fault diagnosis. Background and overview of fault diagnosis this chapter will discuss background of vlsi testing and fault diagnosis. For fault detection, the test which detects the most faults which have not yet been detected, is the best choice. Introduction digital systems produced today are extremely complex in nature.

Dynamic fault diagnosis of combinational and sequential. This paper presents a novel satbased solution for logic diagnosis of multiple faults or design errors in combinational and sequential circuits 18, 19. Later, we will study circuits having a stored internal state, i. Path sensitization for combinational logic circuits one powerful approach to test generation relies on path sensitizing, the applica tion of input such that the output depends directly on the condition of the lead being tested. Dynamic diagnosis of sequential circuits based on stuckat. This method allows designers to perform dynamic fault location of stuckat faults in. The multiple observation times approach was proposed as a test generation approach for fault detection, and was shown to alleviate deficiencies of conventional test generators. The main objective is to design an observer and a corrective controller, so that the stablestate behaviour of.

First, nominal and faulty response waveforms of a circuit are measured, respectively, and then are decomposed into intrinsic mode functions imfs with the eemd method. Next states and outputs are functions of inputs and present states of storage elements 54 two types of sequential circuits. Experimental results are provided for the iscas89 benchmark circuits. It is obvious that when we do so, any singlefaultseeking algorithm would find the second fault candidate a sa0, since now pattern p2 has become a type1 pattern in the modified circuit. A mathematical framework for the testing and diagnosis of sequential machines is developed. One early paper is kantzs study 8 of fault detection techniques for combinational circuits. Acceleration strategies that exploit domain knowledge particular to digital circuits are then proposed. On improving fault diagnosis for synchronous sequential. A fault detection method for combinational circuits. For example in fpgas,the ratio of using combinational circuits to sequential ones varies between 5 to 100 times 17,18.

Easy to build using jk flipflops use the jk 11 to toggle. Theorems for identifying indistinguishable faults in synchronous sequential circuits using their iterative logic arrays and using reachable states, valid states, and states in strongly connected components are presented in section 4. It will present several fault models which constructed to represent the real defects on chips. Us3812337a sequential control circuit having improved.

Keywords genetic algorithm, sequential circuits, automatic test pattern generator, fault coverage, circuit under test, flipflop 1. Fault tolerant design of combinational and sequential. Basically, it results from the fact that direct access to the flipflops in the circuit is not provided. Consist of a combinational circuit to which storage elements are connected to form a feedback path. Dictionary generation is performed once for a given chip and fault model. Sinceinmostapplicationsofthe decision tree thefinal conclusionwill bethatthenetworkis fail 2 reducing the computation time needed for gener. This article describes an emulationbased method for locating stuckat faults in combinational and synchronous sequential circuits. Methods of fault detection in this chapter most of the major techniques of fault detection are described. Some attempts have been made, however, at diagnosis without fault simulation by deducing the location of a fault or faults from the observed. Combinational circuits occupy a considerable portion of processing chips in comparison with sequential circuits. The input to the problem is an implementation of a circuit. Present techniques of sn diagnosis are difficult to apply, and generally lead to lengthy test schedules or additional logic. It will also perform stable state test generation for sequential circuits. Intelligent fault analysis in electrical power grids.

Digital electronics part i combinational and sequential logic. Delay fault diagnosis in synchronous sequential circuits that do not use scandesign is a more difficult problem. Fault diagnosis and logic debugging using boolean satis. A circuit with two crosscoupled nor gates or two crosscoupled nand gates.

Multiple transient fault and multiple upset modeling the problem of the impact of multiple transient faults occurring simultaneously has been addressed in the past, but. This paper presents a novel fault diagnosis method for analog circuits using ensemble empirical mode decomposition eemd, relative entropy, and extreme learning machine elm. The idea behind rnns is to make use of sequential information. Diagnostic fault simulation of sequential circuits citeseerx. A genetic algorithm based two phase fault simulator for. Fault modeling electrical engineering and computer science. Pdf fault detection and test minimization methods for. In contrast to the welldeveloped diagnostic methods for digital circuits, diagnosis for analog circuits is an extremely difficult problem and an active research due to the. The model takes locality aspect of errors and is based on a 3value, nonenumerative analysis technique. The method is based on automatically designing a circuit which implements a closestmatch fault location algorithm specialized for the circuit under diagnosis cud. Digital testing 5 common fault models single stucksingle stuckat faultsat faults transistor open and short faults memory faults pla faults stuckpla faults stuckat, crossat, crossat, crosspoint, bridgingpoint, bridging functional faults processors delay faults transition, path analog faults for more examples, see section 4. Modelbased fault diagnosis of sequential circuits and its.

Dudam2 amit kumar sinha3 1,2,3department of vlsi design 1,3vel tech university, chennai, india 2pune institute of computer technology, pune abstractin any circuit that comprises the logic gates. A similar situation can occur when considering fault location. This invention relates to the architecture, fault detection and diagnostic capabilities of a sequential control circuit, or sequencer. Functional fault equivalence and diagnostic test generation. Proofs is designed puts of sequential circuits starting from an unknown for synchronous sequential circuits and uses the single state. The importance of delay faults proportionally increases when entering in the nanotechnology era, and logic diagnosis must localize delay faults as precisely as possible to speedup yield rampup.

Fault detection tells whether a circuit is fault free or not fault location provides the location of the detected fault. Delay fault diagnosis in sequential circuits request pdf. Studies show the effectiveness of the region based model for single and multiple stuck faults and gate connection errors. Multiple transient faults in combinational and sequential. On the other side, diagnosis of delay faults has received attention for the first category of circuits, but not for synchronous sequential circuits. Functional fault equivalence and diagnostic test generation in combinational logic circuits using conventional atpg andreas veneris1. A sequential circuit is a logical circuit, where the output depends on the present value of the input signal as well as the sequence of past inputs. On improving fault diagnosis for synchronous sequential circuits conference paper pdf available july 1994 with 25 reads how we measure reads. While a combinational circuit is a function of present input only. One major difference from the combination al case is that, for sequential circuits, the. To ensure that only fault free systems are delivered. General terms sequential circuit, flip flop, algorithms et. A fault dictionary is a record of errors caused by modeled faults in a circuit. Fault detection techniques 3 12 fault detection techniques 12.

This paper is concerned with the diagnosis of faults in synchronous sequential machines. Fault diagnosis in digital circuits is normally based on prior computation of fault symptoms using explicit fault models and simulation followed by matching of the observed symptoms of a faulty circuit with one of the sets of precomputed symptoms. In this study, the authors present a novel scheme of faulttolerant control for asynchronous sequential machines. A tracebased method for delay fault diagnosis in synchronous sequential circuits. Efficient modelbased diagnosis of sequential circuits aaai. A model for sequential machine testing and diagnosis. A very general fault model is used in which a faulty machine is represented as a sequential machine, possibly with state and output sets different from those of the good machine. Numerous researches have indicated that analog circuit fault diagnosis is a significant fundamental for design validation and performance evaluation in the integrated circuit manufacturing fields. Abadir3 sep seyedi1 abstract fault equivalence is an essential concept in digital design with signi. Path sensitization method for fault diagnosis in combinational circuits. Fault detection in linear sequential cirucits by aleksa petrovic this thesis is concerned with the detection of non transient faults in digital networks.

Different types of sequential circuits basics and truth. The sequential or combinational testing procedure can both be applied to this technique. In 4, expert system for the diagnosis of faults was discussed. The advance from one state to the next in the sequence is dependent on a combination of external signals from the circuit under. We must develop efficient fault detection and location methods in order to reduce manufacturing costs and time to market. Diagnostic test generation for transition delay faults.

Jul 19, 2015 may 04, 2020 basic concept of fault detection and location in sequential circuits notes edurev is made by best teachers of. The method is, therefore, a hardware solution to the fault detection problem. Algorithms to locate multiple design errors using regionbased model are studied for both combinational and sequential circuits. This method allows designers to perform dynamic fault location of stuckat faults in large. Faults are defined and classified, the problems of detection and. Cheng 159 selects a primary output for fault detection, but unlike marlett, does not restrict propagation. Output is a function of both the present state and the input.

Chap 12 of advanced logical circuits design techniques. On improving fault diagnosis for synchronous sequential circuits. May 04, 2020 basic concept of fault detection and location in sequential circuits notes edurev is made by best teachers of. Sequential fault diagnosis in combinational networks. On improving fault diagnosis for synchronous sequential circuits irith pomeranz and sudhakar m. Two useful states s1, r0 set state q will become to 1. Us3812337a sequential control circuit having improved fault. The faults f1 and f2 are said to be partially distinguishable. Use of the diagnostic fault simulator to diagnose faults, given the output responses of failing devices, is also described.