High reliability against noise, high performance, and low energy consumption are key objectives in the design of on-chip networks. Recently some researchers have considered the impact of various error-control schemes on these objectives and on the tradeoff between them. In all these works performance and reliability are measured separately. However, we will argue in this paper that the use of error-control schemes in on-chip networks results indegradable systems, hence, performance and reliability must be measured jointly using a unified measure, i.e.,performability. Based on the traditional concept of performability, we provide a definition for the ¿Interconnect Performability¿. Analytical models are developed for interconnect performability and expected energy consumption. A detailed comparative analysis of the error-control schemes using the performability analytical models and SPICE simulations is provided taking into consideration voltage swing variations (used to reduce interconnect energy consumption) and variations in wire length. Furthermore, the impact of noise power and time constraint on the effectiveness of error-control schemes are analyzed.

Multiple-voltage is an effective dynamic power reduction design technique, commonly used in low power ICs. To the best of our knowledge there is no reported work for diagnosing multiple-Vdd enabled ICs and the aim of this paper is to propose a method for diagnosing bridge defects in such ICs. Using synthesized ISCAS benchmarks, with realistic extracted bridges and parametric fault model; the paper investigates the impact of varying supply voltage on the accuracy of diagnosis and demonstrates how the additional voltage settings can be leveraged to improve the diagnosis resolution through a novel multi-Vdd diagnosis algorithm.

In this paper, we propose a new SystemC-based fault injection technique that has improved fault representation in visible and on-the-fly data and signal registers. The technique is minimum intrusive since it only requires replacing the original data or signal types to fault injection enabler types. We compare the proposed simulation technique with recently reported SystemC-based techniques and show that our technique has fast simulation speed, better fault representation, while maintaining simplicity and minimum intrusion. We demonstrate fault injection capabilities in a behavioural SystemC description of MPEG-2 decoder using proposed technique and show that up to 98.9% fault representation within data and signal registers can be achieved.

A key design constraint of circuits used in hand-held devices is the power consumption, mainly due to battery-life limitations. Adaptive power management (APM) techniques aim at increasing the battery life of such devices by adjusting the supply voltage and operating frequency, and thus the power consumption, according to the workload. Testing for resistive bridging defects in APM-enabled designs raises a number of challenges due to their complex analog behavior. Testing at more than one supply voltage setting can be employed to improve defect coverage in such systems; however, switching between several supply voltage settings has a detrimental impact on the overall cost of test. This paper proposes a multi- automatic test generation method which delivers 100% resistive bridging defect coverage and also a way of reducing the number of supply voltage settings required during test through test point insertion. The proposed techniques have been experimentally validated using a number of benchmark circuits.

A key design constraint of circuits used in handheld devices is the power consumption, due mainly to the limitations of battery life. The employment of adaptive power management (APM) methods optimizes the power consumption of such circuits. This paper describes an effective APM-aware DFT technique that consists of a Test Generation Suite, including fault list generation, test pattern generation and fault simulation. The test generation suite is capable of generating test patterns for multiple supply voltage (Vdd) settings to maximize coverage of resistive bridging faults; and a method to reduce the number of Vdd settings without compromising the fault coverage in order to reduce the cost of test. Preliminarily validations of the proposed DFT technique using a number of benchmark circuits demonstrate its effectiveness.

In this paper we analyze the test power of SRAM memories and demonstrate that the full functional pre-charge activity is not necessary during test mode because of the predictable addressing sequence. We exploit this observation in order to minimize power dissipation during test by eliminating the unnecessary power consumption associated with the pre-charge activity. This is achieved through a modified pre-charge control circuitry, exploiting the first degree of freedom of March tests, which allows choosing a specific addressing sequence. The efficiency of the proposed solution is validated through extensive Spice simulations

Overheating has been acknowledged as a major problem during the testing of complex system-on-chip integrated circuits. Several power-constrained test-scheduling solutions have been recently proposed to tackle this problem during system integration. However, we show that these approaches cannot guarantee hot-spot-free test schedules because they do not take into account the nonuniform distribution of heat dissipation across the die and the physical adjacency of simultaneously active cores. This paper proposes a new test-scheduling approach that is able to produce short test schedules and guarantee thermal safety at the same time. Two thermal-safe test-scheduling algorithms are proposed. The first algorithm computes an exact (shortest) test schedule that is guaranteed to satisfy a given maximum temperature constraint. The second algorithm is a heuristic intended for complex systems with a large number of embedded cores, for which the exact thermal-safe test-scheduling algorithm may not be feasible. Based on a low-complexity test-session thermal-cost model, this algorithm produces near-optimal length test schedules with significantly less computational effort compared to the optimal algorithm

Recently, the tradeoff between energy consumption and fault-tolerance in real-time systems has been highlighted. These works have focused on dynamic voltage scaling (DVS) to reduce dynamic energy dissipation and on-time redundancy to achieve transient-fault tolerance. While the time redundancy technique exploits the available slack-time to increase the fault-tolerance by performing recovery executions, DVS exploits slack-time to save energy. Therefore, we believe there is a resource conflict between the time-redundancy technique and DVS. The first aim of this paper is to propose the use of information redundancy to solve this problem. We demonstrate through analytical and experimental studies that it is possible to achieve both higher transient fault-tolerance [tolerance to single event upsets (SEUs)] and less energy using a combination of information and time redundancy when compared with using time redundancy alone. The second aim of this paper is to analyze the interplay of transient-fault tolerance (SEU-tolerance) and adaptive body biasing (ABB) used to reduce static leakage energy, which has not been addressed in previous studies. We show that the same technique (i.e., the combination of time and information redundancy) is applicable to ABB-enabled systems and provides more advantages than time redundancy alone.

Overheating has been acknowledged as a major issue in testing complex SoC. Several power constrained system-level DFT solutions (power constrained test scheduling) have recently been proposed to tackle this problem. However as is shown in this paper imposing a chip-level maximum power constraint does not necessarily avoid local overheating due to the nonuniform distribution of power across the chip. This paper proposes a new approach for dealing with overheating during test, by embedding thermal awareness into test scheduling. The proposed approach facilitates rapid generation of thermal-safe test schedules without requiring time-consuming thermal simulations. This is achieved by employing a low-complexity test session thermal model used to guide the test schedule generation algorithm. This approach reduces the chances of a design re-spin due to potential overheating during test.

Concerns about the reliability of real-time embedded systems that employ dynamic voltage scaling has recently been highlighted [1,2,3], focusing on transient-fault-tolerance techniques based on time-redundancy. In this paper we analyze the usage of information redundancy in DVS-enabled systems with the aim of improving both the system tolerance to transient faults as well as the energy consumption. We demonstrate through a case study that it is possible to achieve both higher fault-tolerance and less energy using a combination of information and time redundancy when compared with using time redundancy alone. This even holds despite the impact of the information redundancy hardware overhead and its associated switching activities

Previously reported bus encoding approaches reduce crosstalk delay but they ignore the effects of inductive coupling between the bus lines, i.e. crosstalk noise. Aiming to solve this issue, this paper presents a modified bus-invert technique which minimizes crosstalk noise, as well as delay and power, at the expense of a small area overhead.

Power dissipation during scan testing is becoming an important concern as design sizes and gate densities increase. While several approaches have been recently proposed for reducing power dissipation during the shift cycle (minimum transition don't care fill, special scan cells and scan chain partitioning), very little work has been carried out towards reducing the peak power during test response capture and the few existing approaches for reducing capture power rely on complex ATPG algorithms. This paper proposes a scan architecture with mutually exclusive scan segment activation which overcomes the shortcomings of previous approaches. The proposed architecture achieves both shift and capture power reduction with no impact on the performance of the design, and with minimal impact on area and testing time (typically 2-3%). An algorithmic procedure for assigning flip-flips to scan segments enables reuse of test patterns generated by standard ATPG tools. An implementation of the proposed method had been integrated into an automated design flow using commercial synthesis and simulation tools which was used on a wide range of benchmark designs. Reductions up to 57% in average power, and up to 44% and 34% in peak power dissipation during shift and capture cycles, respectively, were obtained when using two scan segments. Increasing the number of scan segments to six leads to reductions of 96% and 80% in average power and respectively maximum number of simultaneous transitions.

Low power design techniques have been employed for more than two decades, however an emerging problem is satisfying the test power constraints for avoiding destructive test and improving the yield. Our research addresses this problem by proposing a new method which maintains the benefits of mixed-mode built-in self-test (BIST) (low test application time and high fault coverage), and reduces the excessive power dissipation associated with scan-based test. This is achieved by employing dual linear feedback shift register (LFSR) re-seeding and generating mask patterns to reduce the switching activity. Theoretical analysis and experimental results show that the proposed method consistently reduces the switching activity by 25% when compared to the traditional approaches, at the expense of a limited increase in storage requirements.

This paper proposes a power profile manipulation approach which merges two distinct research directions in low power testing: minimization of test power dissipation and test application time reduction under power constraints. It is shown how complementary techniques can be easily combined through this approach to significantly increase test concurrency under power constraints. This is achieved in two steps: in the first step power dissipation is considered a design objective and, consequently, it is minimized; results are further exploited in the second step, when power becomes a design constraint under which the test application time is reduced. A distinctive feature of the proposed power profile manipulation approach is that it can be included in, and consequently improve, any existing power constrained test scheduling algorithm. Extensive experimental results using benchmark circuits, considering test-per-clock, as well as test-per-scan schemes, show that by integrating the proposed power profile manipulation approach into any existing power constrained test scheduling algorithm, savings up to 41 % in test application time are achieved.