@inproceedings{KampmKSIHW2015,
  author = {Kampmann, Matthias and Kochte, Michael A. and Schneider, Eric and Indlekofer, Thomas and Hellebrand, Sybille and Wunderlich, Hans-Joachim},
  title = {{Optimized Selection of Frequencies for Faster-Than-at-Speed Test}},
  booktitle = {Proceedings of the 24th IEEE Asian Test Symposium (ATS'15)},
  year = {2015},
  pages = {109-114},
  keywords = {BIST, small delay defects, delay test, faster-than-at-speed-test},
  abstract = {Small gate delay faults (SDFs) are not detectable at-speed, if they can only be propagated along short paths. These hidden delay faults (HDFs) do not influence the circuit’s behavior initially, but they may indicate design marginalities leading to early-life failures, and therefore they cannot be neglected. HDFs can be detected by faster-than-at-speed test (FAST), where typically several different frequencies are used to maximize the coverage. A given set of test patterns P potentially detects a HDF if it contains a test pattern sensitizing a path through the fault site, and the efficiency of FAST can be measured as the ratio of actually detected HDFs to potentially detected HDFs. The paper at hand targets maximum test efficiency with a minimum number of frequencies. The procedure starts with a test set for transition delay faults and a set of preselected equidistant frequencies. Timing-accurate simulation of this initial setup identifies the hard-to-detect faults, which are then targeted by a more complex timing-aware ATPG procedure. For the yet undetected HDFs, a minimum number of frequencies are determined using an efficient hypergraph algorithm. Experimental results show that with this approach, the number of test frequencies required for maximum test efficiency can be reduced considerably. Furthermore, test set inflation is limited as timing-aware ATPG is only used for a small subset of HDFs.},
  doi = {http://dx.doi.org/10.1109/ATS.2015.26},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2015/ATS_KampmKSIHW2015.pdf}
}

@inproceedings{KochtDBOMW2015,
  author = {Kochte, Michael and Dalirsani, Atefe and Bernabei, Andrea and Omana, Martin and Metra, Cecilia and Wunderlich, Hans-Joachim},
  title = {{Intermittent and Transient Fault Diagnosis on Sparse Code Signatures}},
  booktitle = {Proceedings of the 24th IEEE Asian Test Symposium (ATS'15)},
  year = {2015},
  pages = {157-162},
  keywords = { Diagnosis, intermittent, transient, concurrent error detection, code signature, self-checking, online testing },
  abstract = {Failure diagnosis of field returns typically requires high quality test stimuli and assumes that tests can be repeated. For intermittent faults with fault activation conditions depending on the physical environment, the repetition of tests cannot ensure that the behavior in the field is also observed during diagnosis, causing field returns diagnosed as no-trouble-found. In safety critical applications, self-checking circuits, which provide concurrent error detection, are frequently used. To diagnose intermittent and transient faulty behavior in such circuits, we use the stored encoded circuit outputs in case of a failure (called signatures) for later analysis in diagnosis. For the first time, a diagnosis algorithm is presented that is capable of performing the classification of intermittent or transient faults using only the very limited amount of functional stimuli and signatures observed during operation and stored on chip. The experimental results demonstrate that even with these harsh limitations it is possible to distinguish intermittent from transient faulty behavior. This is essential to determine whether a circuit in which failures have been observed should be subject to later physical failure analysis, since intermittent faulty behavior has been diagnosed. In case of transient faulty behavior, it may still be operated reliably.},
  doi = {http://dx.doi.org/10.1109/ATS.2015.34},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2015/ATS_KochtDBOMW2015.pdf}
}

@inproceedings{LiuKW2015,
  author = {Liu, Chang and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Efficient Observation Point Selection for Aging Monitoring}},
  booktitle = {Proceedings of the 21st IEEE International On-Line Testing Symposium (IOLTS'15)},
  year = {2015},
  pages = {176--181},
  keywords = {Aging monitoring, delay monitoring, online test, concurrent test, stability checker, path selection},
  abstract = {Circuit aging causes a performance degradation and eventually a functional failure. It depends on the workload and the environmental condition of the system, which are hard to predict in early design phases resulting in pessimistic worst case design. Existing delay monitoring schemes measure the remaining slack of paths in the circuit, but cause a significant hardware penalty including global wiring. More importantly, the low sensitization ratio of long paths in applications may lead to a very low measurement frequency or even an unmonitored timing violation. In this work, we propose a delay monitor placement method by analyzing the topological circuit structure and sensitization of paths. The delay monitors are inserted at meticulously selected positions in the circuit, named observation points (OPs). This OP monitor placement method can reduce the number of inserted monitors by up to 98% compared to a placement at the end of long paths. The experimental validation shows the effectiveness of this aging indication, i.e. a monitor issues a timing alert always earlier than any imminent timing failure.},
  doi = {http://dx.doi.org/10.1109/IOLTS.2015.7229855},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2015/IOLTS_LiuKW2015.pdf}
}

@article{BaranKW2015a,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Fine-Grained Access Management in Reconfigurable Scan Networks}},
  journal = {IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems (TCAD)},
  year = {2015},
  volume = {34},
  number = {6},
  pages = {937--946},
  keywords = {Debug and diagnosis, reconfigurable scan network, IJTAG, IEEE Std 1687, secure DFT, hardware security, instrument protection},
  abstract = {Modern VLSI designs incorporate a high amount of instrumentation that supports post-silicon validation and debug, volume test and diagnosis, as well as in-field system monitoring and maintenance. Reconfigurable scan architectures, as allowed by the novel IEEE Std 1149.1-2013 (JTAG) and IEEE Std 1687- 2014 (IJTAG), emerge as a scalable mechanism for access to such on-chip instruments. While the on-chip instrumentation is crucial for meeting quality, dependability, and time-to-market goals, it is prone to abuse and threatens system safety and security. A secure access management method is mandatory to assure that critical instruments be accessible to authorized entities only. This work presents a novel protection method for fine-grained access management in complex reconfigurable scan networks based on a challenge-response authentication protocol. The target scan network is extended with an authorization instrument and Secure Segment Insertion Bits (S²IB) that together control the accessibility of individual instruments. To the best of the authors’ knowledge, this is the first fine-grained access management scheme that scales well with the number of protected instruments and offers a high level of security. Compared with recent stateof- the-art techniques, this scheme is more favorable with respect to implementation cost, performance overhead, and provided security level.},
  doi = {http://dx.doi.org/10.1109/TCAD.2015.2391266},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2015/TCAD_BaranKW2015.pdf}
}

@inproceedings{BaranFKLWT2015,
  author = { Baranowski, Rafal and Firouzi, Farshad and Kiamehr, Saman and Liu, Chang and Tahoori, Mehdi and Wunderlich, Hans-Joachim },
  title = {{On-Line Prediction of NBTI-induced Aging Rates}},
  booktitle = {Proceedings of the ACM/IEEE Conference on Design, Automation and Test in Europe (DATE'15)},
  year = {2015},
  pages = {589--592},
  keywords = {Representative critical gates, Workload monitoring, Aging prediction, NBTI},
  abstract = {Nanoscale technologies are increasingly susceptible to aging processes such as Negative-Bias Temperature Instability (NBTI) which undermine the reliability of VLSI systems. Existing monitoring techniques can detect the violation of safety margins and hence make the prediction of an imminent failure possible. However, since such techniques can only detect measurable degradation effects which appear after a relatively long period of system operation, they are not well suited to early aging prediction and proactive aging alleviation. This work presents a novel method for the monitoring of NBTI-induced degradation rate in digital circuits. It enables the timely adoption of proper mitigation techniques that reduce the impact of aging. The developed method employs machine learning techniques to find a small set of so called Representative Critical Gates (RCG), the workload of which is correlated with the degradation of the entire circuit. The workload of RCGs is observed in hardware using so called workload monitors. The output of the workload monitors is evaluated on-line to predict system degradation experienced within a configurable (short) period of time, e.g. a fraction of a second. Experimental results show that the developed monitors predict the degradation rate with an average error of only 1.6% at 4.2% area overhead.},
  url = { http://dl.acm.org/citation.cfm?id=2755886 },
  doi = {http://dx.doi.org/10.7873/DATE.2015.0940},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2015/DATE_BaranFKLTW2015.pdf}
}

@article{BaranKW2014a,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Access Port Protection for Reconfigurable Scan Networks}},
  journal = {Journal of Electronic Testing: Theory and Applications (JETTA)},
  publisher = {Springer-Verlag},
  year = {2014},
  volume = {30},
  number = {6},
  pages = {711--723},
  keywords = {Debug and diagnosis, reconfigurable scan network, IJTAG, IEEE P1687, secure DFT, hardware security},
  abstract = {Scan infrastructures based on IEEE Std. 1149.1 (JTAG), 1500 (SECT), and P1687 (IJTAG) provide a cost-effective access mechanism for test, reconfiguration, and debugging purposes. The improved accessibility of on-chip instruments, however, poses a serious threat to system safety and security. While state-of-theart protection methods for scan architectures compliant with JTAG and SECT are very effective, most of these techniques face scalability issues in reconfigurable scan networks allowed by the upcoming IJTAG standard. This paper describes a scalable solution for multilevel access management in reconfigurable scan networks. The access to protected instruments is restricted locally at the interface to the network. The access restriction is realized by a sequence filter that allows only a precomputed set of scan-in access sequences. This approach does not require any modification of the scan architecture and causes no access time penalty. Therefore, it is well suited for core-based designs with hard macros and 3D integrated circuits. Experimental results for complex reconfigurable scan networks show that the area overhead depends primarily on the number of allowed accesses, and is marginal even if this number exceeds the count of registers in the network.},
  url = { http://link.springer.com/article/10.1007/s10836-014-5484-2 },
  doi = {http://dx.doi.org/10.1007/s10836-014-5484-2},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2014/JETTA_BaranKW2014.pdf}
}

@inproceedings{JutmaSW2014,
  author = {Jutman, Artur and Sonza Reorda, Matteo and Wunderlich, Hans-Joachim},
  title = {{High Quality System Level Test and Diagnosis}},
  booktitle = {Proceedings of the 23rd IEEE Asian Test Symposium (ATS'14)},
  year = {2014},
  pages = {298--305},
  keywords = {System test, board test, diagnosis},
  abstract = {This survey introduces into the common practices, current challenges and advanced techniques of high quality system level test and diagnosis. Specialized techniques and industrial standards of testing complex boards are introduced. The reuse for system test of design for test structures and test data developed at chip level is discussed, including the limitations and research challenges. Structural test methods have to be complemented by functional test methods. State-of-the-art and leading edge research for functional testing will be covered.},
  doi = {http://dx.doi.org/10.1109/ATS.2014.62},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2014/ATS_JutmaSW2014.pdf}
}

@inproceedings{ImhofW2014,
  author = {Imhof, Michael E. and Wunderlich, Hans-Joachim},
  title = {{Bit-Flipping Scan - A Unified Architecture for Fault Tolerance and Offline Test}},
  booktitle = {Proceedings of the Design, Automation and Test in Europe (DATE'14)},
  year = {2014},
  keywords = {Bit-Flipping Scan, Fault Tolerance, Test, Compaction, ATPG, Satisfiability},
  abstract = {Test is an essential task since the early days of digital circuits. Every produced chip undergoes at least a production test supported by on-chip test infrastructure to reduce test cost. Throughout the technology evolution fault tolerance gained importance and is now necessary in many applications to mitigate soft errors threatening consistent operation. While a variety of effective solutions exists to tackle both areas, test and fault tolerance are often implemented orthogonally, and hence do not exploit the potential synergies of a combined solution.
The unified architecture presented here facilitates fault tolerance and test by combining a checksum of the sequential state with the ability to flip arbitrary bits. Experimental results
confirm a reduced area overhead compared to a orthogonal combination of classical test and fault tolerance schemes. In combination with heuristically generated test sequences the test
application time and test data volume are reduced significantly.},
  url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6800407},
  doi = {http://dx.doi.org/10.7873/DATE.2014.206},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2014/DATE_ImhofW2014.pdf}
}

@inproceedings{BaranKW2014,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Verifikation Rekonfigurierbarer Scan-Netze}},
  booktitle = {Proceedings of the 17. Workshop Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen (MBMV'14)},
  year = {2014},
  pages = {137--146},
  keywords = {Verification, debug and diagnosis, reconfigurable scan network, IJTAG, IEEE P1687, design for test},
  abstract = {Rekonfigurierbare Scan-Netze, z. B. entsprechend IEEE Std. P1687 oder 1149.1-2013, ermöglichen den effizienten Zugriff auf On-Chip-Infrastruktur für Bringup, Debug, Post-Silicon-Validierung und Diagnose. Diese Scan-Netze sind oft hierarchisch und können komplexe strukturelle und funktionale Abhängigkeiten aufweisen. Bekannte Verfahren zur Verifikation von Scan-Ketten, basierend auf Simulation und struktureller Analyse, sind nicht geeignet, Korrektheitseigenschaften von komplexen Scan-Netzen zu verifizieren. Diese Arbeit stellt ein formales Modell für rekonfigurierbare Scan-Netze vor, welches die strukturellen und funktionalen Abhängigkeiten abbildet und anwendbar ist für Architekturen nach IEEE P1687. Das Modell dient als Grundlage für effizientes Bounded Model Checking von Eigenschaften, wie z. B. der Erreichbarkeit von Scan-Registern.},
  url = {https://cuvillier.de/de/shop/publications/6629-mbmv-2014},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2014/MBMV_BaranKW2014.pdf}
}

@inproceedings{BaranKW2013a,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Securing Access to Reconfigurable Scan Networks}},
  booktitle = {Proceedings of the 22nd IEEE Asian Test Symposium (ATS'13)},
  year = {2013},
  keywords = {Debug and diagnosis, reconfigurable scan network, IJTAG, IEEE P1687, secure DFT, hardware security},
  abstract = {The accessibility of on-chip embedded infrastructure for test, reconfiguration, and debug poses a serious safety and security problem. Special care is required in the design and development of scan architectures based on IEEE Std. 1149.1 (JTAG), IEEE Std. 1500, and especially reconfigurable scan networks, as allowed by the upcoming IEEE P1687 (IJTAG). Traditionally, the scan infrastructure is secured after manufacturing test using fuses that disable the test access port (TAP) completely or partially. The fuse-based approach is efficient if some scan chains or instructions of the TAP controller are to be permanently blocked. However, this approach becomes costly if fine-grained access management is required, and it faces scalability issues in reconfigurable scan networks. In this paper, we propose a scalable solution for multi-level access management in reconfigurable scan networks. The access to protected registers is restricted locally at TAP-level by a sequence filter which allows only a precomputed set of scan-in access sequences. Our approach does not require any modification of the scan architecture and causes no access time penalty. Experimental results for complex reconfigurable scan networks show that the area overhead depends primarily on the number of allowed accesses, and is marginal even if this number exceeds the count of network’s registers.},
  doi = {http://dx.doi.org/10.1109/ATS.2013.61},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2013/ATS_BaranKW2013.pdf}
}

@inproceedings{BaranCILW2013,
  author = {Baranowski, Rafal and Cook, Alejandro and Imhof, Michael E. and Liu, Chang and Wunderlich, Hans-Joachim},
  title = {{Synthesis of Workload Monitors for On-Line Stress Prediction}},
  booktitle = {Proceedings of the 16th IEEE Symp. Defect and Fault Tolerance in VLSI and Nanotechnology Systems (DFT'13)},
  year = {2013},
  pages = {137--142},
  keywords = {Reliability estimation, workload monitoring, aging prediction, NBTI},
  abstract = {Stringent reliability requirements call for monitoring mechanisms to account for circuit degradation throughout the complete system lifetime. In this work, we efficiently monitor the stress experienced by the system as a result of its current workload. To achieve this goal, we construct workload monitors that observe the most relevant subset of the circuit’s primary and pseudo-primary inputs and produce an accurate stress approximation. The proposed approach enables the timely adoption of
suitable countermeasures to reduce or prevent any deviation from the intended circuit behavior. The relation between monitoring accuracy and hardware cost can be adjusted according to design requirements. Experimental results show the efficiency of the proposed approach for the prediction of stress induced by Negative Bias Temperature Instability (NBTI) in critical and near-critical paths of a digital circuit.},
  url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6653596},
  doi = {http://dx.doi.org/10.1109/DFT.2013.6653596},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2013/DFTS_BaranCILW2013.pdf}
}

@inproceedings{BaranKW2013,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Scan Pattern Retargeting and Merging with Reduced Access Time}},
  booktitle = {Proceedings of the IEEE European Test Symposium (ETS'13)},
  publisher = {IEEE Computer Society},
  year = {2013},
  pages = {39--45},
  keywords = {Design for debug & diagnosis, optimal pattern retargeting, scan pattern generation, reconfigurable scan network, IJTAG, P1687},
  abstract = {Efficient access to on-chip instrumentation is a key enabler for post-silicon validation, debug, bringup or diagnosis. Re- configurable scan networks, as proposed by e.g. the IEEE Std. P1687, emerge as an effective and affordable means to cope with the increasing complexity of on-chip infrastructure. To access an element in a reconfigurable scan network, a scan- in bit sequence must be generated according to the current state and structure of the network. Due to sequential and combinational dependencies, the scan pattern generation process (pattern retargeting) poses a complex decision and optimization problem. This work presents a method for scan pattern generation with reduced access time. We map the access time reduction to a pseudo- Boolean optimization problem, which enables the use of efficient solvers to exhaustively explore the search space of valid scan-in sequences. This is the first automated method for efficient pattern retargeting in complex reconfigurable scan architectures such as P1687- based networks. It supports the concurrent access to multiple target scan registers (access merging) and generates reduced (short) scan-in sequences, considering all sequential and combinational dependencies. The proposed method achieves an access time reduction by up to 88x or 2.4x in average w.r.t. unoptimized satisfying solutions.},
  doi = {http://dx.doi.org/10.1109/ETS.2013.6569354},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2013/ETS_BaranKW2013.pdf}
}

@inproceedings{BaranKW2012,
  author = {Baranowski, Rafal and Kochte, Michael A. and Wunderlich, Hans-Joachim},
  title = {{Modeling, Verification and Pattern Generation for Reconfigurable Scan Networks}},
  booktitle = {Proceedings of the IEEE International Test Conference (ITC'12)},
  publisher = {IEEE Computer Society},
  year = {2012},
  pages = {1--9},
  keywords = {Reconfigurable scan network, Pattern generation, Pattern retargeting, DFT, IJTAG, P1687},
  abstract = {Reconfigurable scan architectures allow flexible integration and efficient access to infrastructure in SoCs, e.g. for test, diagnosis, repair or debug. Such scan networks are often hierarchical and have complex structural and functional dependencies. For instance, the IEEE P1687 proposal, known as IJTAG, allows integration of multiplexed scan networks with arbitrary internal control signals. Common approaches for scan verification based on static structural analysis and functional simulation are not sufficient to ensure correct operation of these types of architectures. Hierarchy and flexibility may result in complex or even contradicting configuration requirements to access single elements. Sequential logic justification is therefore mandatory both to verify the validity of a scan network, and to generate the required access sequences. This work presents a formal method for verification of reconfigurable scan architectures, as well as pattern retargeting, i.e. generation of required scan-in data. The method is based on a formal model of structural and functional dependencies. Network verification and pattern retargeting is mapped to a Boolean satisfiability problem, which enables the use of efficient SAT solvers to exhaustively explore the search space of valid scan configurations.},
  doi = {http://dx.doi.org/10.1109/TEST.2012.6401555},
  file = {http://www.iti.uni-stuttgart.de/fileadmin/rami/files/publications/2012/ITC_BaranKW2012.pdf}
}