BIST test pattern generator based on partitioning circuit inputs

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 33-35).by Clara Sánchez.M.Eng

Acceleration of Seed Ordering and Selection for High Quality Delay Test

Seed ordering and selection is a key technique to provide high-test quality with limited resources in Built-In Self Test (BIST) environment. We present a hard-to-detect delay fault selection method to accelerate the computation time in seed ordering and selection processes. This selection method can be used to restrict faults for test generation executed in an early stage in seed ordering and selection processes, and reduce a test pattern count and therefore a computation time. We evaluate the impact of the selection method both in deterministic BIST, where one test pattern is decoded from one seed, and mixed-mode BIST, where one seed is expanded to two or more patterns. The statistical delay quality level (SDQL) is adopted as test quality measure, to represent ability to detect small delay defects (SDDs). Experimental results show that our proposed method can significantly reduce computation time from 28% to 63% and base set seed counts from 21% to 67% while slightly sacrificing test quality

A Hardware Security Solution against Scan-Based Attacks

Scan based Design for Test (DfT) schemes have been widely used to achieve high fault coverage for integrated circuits. The scan technique provides full access to the internal nodes of the device-under-test to control them or observe their response to input test vectors. While such comprehensive access is highly desirable for testing, it is not acceptable for secure chips as it is subject to exploitation by various attacks. In this work, new methods are presented to protect the security of critical information against scan-based attacks. In the proposed methods, access to the circuit containing secret information via the scan chain has been severely limited in order to reduce the risk of a security breach. To ensure the testability of the circuit, a built-in self-test which utilizes an LFSR as the test pattern generator (TPG) is proposed. The proposed schemes can be used as a countermeasure against side channel attacks with a low area overhead as compared to the existing solutions in literature

Impact of LFSR Seeding on the Test Pattern Generator in BIST

This paper considers the problem of minimizing the power required to test a BIST based combinational circuit without modifying the test pattern generator and with no extra area or delay overhead. The objective of this paper is to analyze the impact of the polynomial and seed selection of the LFSR on the power consumed by the circuit. It is shown that proper selection of the seed of the LFSR can lead to significant decrease in the power consumption of the BIST sessions. For this purpose, a Bit Flipping LFSR is used as a test pattern generator in the BIST design. Experimental results using the ISCAS benchmark circuits are reported, showing variations of the seed selected for the LFSR, the power consumed is ranging from 5.5% to 13.5%

Design of a 1.9 GHz low-power LFSR circuit using the Reed-Solomon algorithm for Pseudo-Random Test Pattern Generation

A linear feedback shift register (LFSR) has been frequently used in the Built-in Self-Test (BIST) designs for the pseudo-random test pattern generation. The volume of the test patterns and test power dissipation are the key features in the large complex designs. The objective of this paper is to propose a new LFSR circuit based on the proposed Reed-Solomon (RS) algorithm. The RS algorithm is created by considering the factors of the maximum length test pattern with a minimum distance over the time. Also, it has achieved an effective generation of test patterns over a stage of complexity order O (m log2 m), where m denotes the total number of message bits. We analyzed our RS LFSR mathematically using the feedback polynomial function for an area-sensitive design. However, the bit-wise stages of the proposed RS LFSR are simulated using the TSMC 130 nm IC design tool in the Mentor Graphics platform. Experimental results showed that the proposed LFSR achieved the effective pseudo-random test patterns with a low-test power dissipation (25.13 µW). Ultimately, the circuit has operated in the highest operating frequency (1.9 GHz) environment.   &nbsp

Power Minimisation Techniques for Testing Low Power VLSI Circuits (PhD Dissertation)

Testing low power very large scale integrated (VLSI) circuits has recently become an area of concern due to yield and reliability problems. This dissertation focuses on minimising power dissipation during test application at logic level and register-transfer level (RTL) of abstraction of the VLSI design flow. The first part of this dissertation addresses power minimisation techniques in scan sequential circuits at the logic level of abstraction. A new best primary input change (BPIC) technique based on a novel test application strategy has been proposed. The technique increases the correlation between successive states during shifting in test vectors and shifting out test responses by changing the primary inputs such that the smallest number of transitions is achieved. The new technique is test set dependent and it is applicable to small to medium sized full and partial scan sequential circuits. Since the proposed test application strategy depends only on controlling primary input change time, power is minimised with no penalty in test area, performance, test efficiency, test application time or volume of test data. Furthermore, it is shown that partial scan does not provide only the commonly known benefits such as less test area overhead and test application time, but also less power dissipation during test application when compared to full scan. To achieve power savings in large scan sequential circuits a new test set independent multiple scan chain-based technique which employs a new design for test (DFT) architecture and a novel test application strategy, is presented. The technique has been validated using benchmark examples, and it has been shown that power is minimised with low computational time, low overhead in test area and volume of test data, and with no penalty in test application time, test efficiency, or performance. The second part of this dissertation addresses power minimisation techniques for testing low power VLSI circuits using built-in self-test (BIST) at RTL. First, it is important to overcome the shortcomings associated with traditional BIST methodologies. It is shown how a new BIST methodology for RTL data paths using a novel concept called test compatibility classes (TCC) overcomes high test application time, BIST area overhead, performance degradation, volume of test data, fault-escape probability, and complexity of the testable design space exploration. Second, power minimisation in BIST RTL data paths is achieved by analysing the effect of test synthesis and test scheduling on power dissipation during test application and by employing new power conscious test synthesis and test scheduling algorithms. Third, the new BIST methodology has been validated using benchmark examples. Further, it is shown that when the proposed power conscious test synthesis and test scheduling is combined with novel test compatibility classes simultaneous reduction in test application time and power dissipation is achieved with low overhead in computational time

Built-In Self-Test (BIST) for Multi-Threshold NULL Convention Logic (MTNCL) Circuits

This dissertation proposes a Built-In Self-Test (BIST) hardware implementation for Multi-Threshold NULL Convention Logic (MTNCL) circuits. Two different methods are proposed: an area-optimized topology that requires minimal area overhead, and a test-performance-optimized topology that utilizes parallelism and internal hardware to reduce the overall test time through additional controllability points. Furthermore, an automated software flow is proposed to insert, simulate, and analyze an input MTNCL netlist to obtain a desired fault coverage, if possible, through iterative digital and fault simulations. The proposed automated flow is capable of producing both area-optimized and test-performance-optimized BIST circuits and scripts for digital and fault simulation using commercial software that may be utilized to manually verify or adjust further, if desired