Mohammad Hosseinabady

A concurrent testing method for NoC switches

This paper proposes reuse of on-chip networks for testing switches in network on chips (NoCs). The proposed algorithm broadcasts test vectors of switches through the on-chip networks and detects faults by comparing output responses of switches with each other. This algorithm alleviates the need for: (1) external comparison of the output response of the circuit-under-test with the response of a fault free circuit stored on a tester (2) on-chip signature analysis (3) a dedicated test-bus to reach test vectors and collect their responses. Experimental results on a few test benches compare the proposed algorithm with traditional system on chip (SoC) test methods

Simultaneous Reduction of Dynamic and Static Power in Scan Structures

Power dissipation during test is a major challenge in testing integrated circuits. Dynamic power has been the dominant part of power dissipation in CMOS circuits, however, in future technologies the static portion of power dissipation will outreach the dynamic portion. This paper proposes an efficient technique to reduce both dynamic and static power dissipation in scan structures. Scan cell outputs which are not on the critical path(s) are multiplexed to fixed values during scan mode. These constant values and primary inputs are selected such that the transitions occurring on nonmultiplexed scan cells are suppressed and the leakage current during scan mode is decreased. A method for finding these vectors is also proposed. The effectiveness of this technique is proved by experiments performed on ISCAS89 benchmark circuits.

Using the inter- and intra-switch regularity in NoC switch testing

This paper proposes an efficient test methodology to test switches in a network-on-chip (NoC) architecture. A switch in a NoC consists of a number of ports and a router. Using the intra-switch regularity among ports of a switch and inter-switch regularity among routers of switches, the proposed method decreases the test application time and test data volume of NoC testing. Using a test source to generate test vectors and scan-based testing, this methodology broadcasts test vectors through the minimum spanning tree of the NoC and concurrently tests its switches. In addition, a possible fault is detected by comparing test results using inter- or intra- switch comparisons. The logic and memory parts of a switch are tested by appropriate memory and logic testing methods. Experimental results show less test application time and test power consumption, as compared with other methods in the literature

An Analytical Model for Reliability Evaluation of NoC Architectures

This paper proposes an analytical model to assess Reliability Factor of an NoC based System-on-Chip design. Reliability Factor is the probability that faults in the NoC infrastructure can be recovered without any effect on system functionality. The proposed method classifies switch faults of an NoC according to their impact on system functionality. Based on this classification, the contribution of each transient fault lowering the reliability of the NoC is calculated. This model can be used to decide which fault tolerant techniques cause more improvement on system reliability.

Single-Event Upset Analysis and Protection in High Speed Circuits

The effect of single-event transients (SETs) (at a combinational node of a design) on the system reliability is becoming a big concern for ICs manufactured using advanced technologies. An SET at a node of combinational part may cause a transient pulse at the input of a flip-flop and consequently is latched in the flip-flop and generates a soft-error. When an SET conjoined with a transition at a node along a critical path of the combinational part of a design, a transient delay fault may occur at the input of a flip-flop. On the other hand, increasing pipeline depth and using low power techniques such as multi-level power supply, and multi-threshold transistor convert almost all paths in a circuit to critical ones. Thus, studying the behavior of the SET in these kinds of circuits needs special attention. This paper studies the dynamic behavior of a circuit with massive critical paths in the presence of an SET. We also propose a novel flip-flop architecture to mitigate the effects of such SETs in combinational circuits. Furthermore, the proposed architecture can tolerant a single event upset (SEU) caused by particle strike on the internal nodes of a flip-flop

A UML Based System Level Failure Rate Assessment Technique for SoC Designs

This paper proposes an analytical method to assess soft-error rate (SER) in the early stages of a system-on-chip (SoC) platform-based design methodology. The proposed method uses an executable UML model of the SoC for its input. Soft-errors on the design are modeled by disturbances on the value of attributes in the classes of the UML model and disturbances on opcodes of software cores. SER and execution time of each core in the SoC and a failure modes and effects analysis (FMEA) that determines the severity of each failure mode in the SoC are used to compute the system-failure rate (SFR) of the SoC

A Selective Trigger Scan Architecture for VLSI Testing

Time, power, and data volume are among some of the most challenging issues for testing System-on-Chip (SoC) and have not been fully resolved even if a scan-based technique is employed. A novel architecture referred to the Selective Trigger Scan architecture, is introduced in this paper to address these issues. This architecture reduces switching activity in the circuitunder-test (CUT) and increases the clock frequency of the scanning process. An auxiliary chain is utilized in this architecture to avoid the large number of transitions to the CUT during the scan-in process, as well as enabling retention of the currently applied test vectors and applying only necessary changes to them. The auxiliary chain shifts in the difference between consecutive test vectors and only the required transitions (referred to as trigger data) are applied to the CUT. Power requirements are substantially reduced; moreover, DFT penalties are reduced because no additional multiplexer is utilized along the scan path. Data reformatting is applied in order to make the proposed architecture amenable to data compression, thus permitting a further reduction in test time. It also permits delay fault testing. Using ISCAS 85 and 89 benchmark circuits, the effectiveness of this architecture for improving SoC test measures (such as power, time and data volume) is experimentally evaluated and confirmed.

Analysis of System-Failure Rate Caused by Soft-Errors using a UML-Based Systematic Methodology in an SoC

This paper proposes an analytical method to assess the soft-error rate (SER) in the early stages of a System-on-Chip (SoC) platform-based design methodology. The proposed method gets an executable UML (Unified Modeling Language) model of the SoC and the raw soft- error rate of different parts of the platform as its inputs. Soft-errors on the design are modeled by disturbances on the value of attributes in the classes of the UML model and disturbances on opcodes of software cores. The Dynamic behavior of each core is used to determine the propagation probability of each variable disturbance to the core outputs. Furthermore, the SER and the execution time of each core in the SoC and a Failure Modes and Effects Analysis (FMEA) that determines the severity of each failure mode in the SoC are used to compute the System-Failure Rate (SFR) of the SoC.

Low overhead DFT using CDFG by modifying controller

A novel design-for-test (DFT) method that requires minor modifications to the controller in the register-transfer level (RTL) description of a circuit is presented. The control/data flow graph representation of an RTL circuit is used for analysing the testability of individual RTL operations within the RTL circuit. Using a non-scan arrangement, existing data paths are utilised to provide controllability and observability to RTL operations. Furthermore, additional data paths are introduced by altering the controller states or adding new transitions. This method considerably reduces the test application time by ignoring unnecessary control states in the test process. The proposed method is applied to behavioural and RTL benchmarks. The results show the effectiveness of this method when compared with some other DFT insertion methods.

A Flow Graph Technique for DFT Controller Modification

This paper presents a novel DFT method which requires very small modification to a controller in RT-level description of a circuit. The control/data flow graph (CDFG) representation of an RTL circuit is used for analyzing the testability of individual RT-level operations within a hierarchical test technique. Using a non-scan arrangement, existing data paths are utilized to provide controllability and observability to RT-level operations. Furthermore, additional data paths are introduced by altering the controller states or signals. Post behavioral synthesis information and pre-computed test vectors of the individual modules are utilized. This method considerably reduces the test application time by ignoring unnecessary control states in the test process