Theory, design and application of gradient adaptive lattice filters

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Testability and redundancy techniques for improved yield and reliability of CMOS VLSI circuits

The research presented in this thesis is concerned with the design of fault-tolerant integrated circuits as a contribution to the design of fault-tolerant systems. The economical manufacture of very large area ICs will necessitate the incorporation of fault-tolerance features which are routinely employed in current high density dynamic random access memories. Furthermore, the growing use of ICs in safety-critical applications and/or hostile environments in addition to the prospect of single-chip systems will mandate the use of fault-tolerance for improved reliability. A fault-tolerant IC must be able to detect and correct all possible faults that may affect its operation. The ability of a chip to detect its own faults is not only necessary for fault-tolerance, but it is also regarded as the ultimate solution to the problem of testing. Off-line periodic testing is selected for this research because it achieves better coverage of physical faults and it requires less extra hardware than on-line error detection techniques. Tests for CMOS stuck-open faults are shown to detect all other faults. Simple test sequence generation procedures for the detection of all faults are derived. The test sequences generated by these procedures produce a trivial output, thereby, greatly simplifying the task of test response analysis. A further advantage of the proposed test generation procedures is that they do not require the enumeration of faults. The implementation of built-in self-test is considered and it is shown that the hardware overhead is comparable to that associated with pseudo-random and pseudo-exhaustive techniques while achieving a much higher fault coverage through-the use of the proposed test generation procedures. The consideration of the problem of testing the test circuitry led to the conclusion that complete test coverage may be achieved if separate chips cooperate in testing each other's untested parts. An alternative approach towards complete test coverage would be to design the test circuitry so that it is as distributed as possible and so that it is tested as it performs its function. Fault correction relies on the provision of spare units and a means of reconfiguring the circuit so that the faulty units are discarded. This raises the question of what is the optimum size of a unit? A mathematical model, linking yield and reliability is therefore developed to answer such a question and also to study the effects of such parameters as the amount of redundancy, the size of the additional circuitry required for testing and reconfiguration, and the effect of periodic testing on reliability. The stringent requirement on the size of the reconfiguration logic is illustrated by the application of the model to a typical example. Another important result concerns the effect of periodic testing on reliability. It is shown that periodic off-line testing can achieve approximately the same level of reliability as on-line testing, even when the time between tests is many hundreds of hours

1994 OURE report, including the 4th Annual UMR Undergraduate Research Symposium -- Entire Proceedings

The Opportunities for Undergraduate Research Experience program began in 1990. This volume constitutes the proceedings of the fourth annual OURE program. The goals of the program are: (1) to expand opportunities for a more active form of learning by students; (2) to encourage the direct interaction of undergraduate students with faculty through research; (3) to expand the level of research activity on the campus; (4) to help encourage superior students to pursue graduate study; and (5) to reinforce the idea that teaching and research are compatible and mutually reinforcing at a research university. The OURE program continues to achieve its goals -- UMR students have performed research on a wide variety of topics, have worked closely with faculty and have experienced first-hand both the excitement and the frustration of performing research. This volume contains papers presented at the fourth annual UMR Undergraduate Research Symposium held on March 23, 1994, and final reports of students participating in the 1993-94 OURE program. Students in the OURE program are encouraged to participate in the Symposium and participation increased substantially this year. Through programs such as this, the University of Missouri--Rolla, Missouri’s Technological University, continues to provide opportunities for its undergraduate students to further their research experiences in preparation for their future endeavors