Digital Designs

About: Digital Designs is a based out in . It is known for research contribution in the topics: Automatic test pattern generation & Design for testing. The organization has 199 authors who have published 179 publications receiving 2576 citations.

Test wrapper and test access mechanism co-optimization for system-on-chip

Abstract: Test access mechanisms (TAMs) and test wrappers are integral parts of a system-on-chip (SoC) test architecture. Prior research has concentrated on only one aspect of the TAM/wrapper design problem at a time, i.e., either optimizing the TAMs for a set of pre-designed wrappers, or optimizing the wrapper for a given TAM width. In this paper, we address a more general problem, that of carrying out TAM design and wrapper optimization in conjunction. We present an efficient algorithm to construct wrappers that reduce the testing time for cores. Our wrapper design algorithm improves on earlier approaches by also reducing the TAM width required to achieve these lower testing times. We present new mathematical models for TAM optimization that use the core testing time values calculated by our wrapper design algorithm. We further present a new enumerative method for TAM optimization that reduces execution time significantly when the number of TAMs being designed is small. Experimental results are presented for an academic SoC as well as an industrial SoC.

A set of benchmarks for modular testing of SOCs

Abstract: This paper presents the ITC'02 SOC test benchmarks. The purpose of this new benchmark set is to stimulate research into new methods and tools for modular testing of SOCs and to enable the objective comparison of such methods and tools with respect to effectiveness and efficiency. The paper defines the benchmark format and naming scheme, and presents the benchmark SOCs. In addition, it provides an overview of the research problems that can be addressed and evaluated by means of this benchmark set. These research problems include the design of optimized test access infrastructures and test schedules.

Wrapper design for embedded core test

Abstract: A wrapper is a thin shell around the core, that provides the switching between functional, and core-internal and core-external test modes. Together with a test access mechanism (TAM), the core test wrapper forms the test access infrastructure to embedded reusable cores. Various company-internal as well as industry-wide standardized but scalable wrappers have been proposed. This paper deals with the design of such core test wrappers. It gives a general architecture for wrappers, and describes how a wrapper can be built up from a library of wrapper cells which are selected on basis of the terminal types of the core. We show that the ordering and partitioning of wrapper cells and core-internal scan chains over TAM chains determine the test time of the core. An heuristic approach for the NP-hard problem of partitioning the TAM chain items for minimal test time is presented and its usage is illustrated by means of an example. Finally we sketch how wrapper generation and verification can be automated.

Effective and efficient test architecture design for SOCs

Abstract: This paper deals with the design of test architectures for modular SOC testing. These architectures consist of wrappers and TAMs (test access mechanisms). For a given SOC, with specified parameters of modules and their tests, we design architectures which minimize the required ATE vector memory depth and test application time. In this paper, we formulate the problems of test architecture design both for modules with fixed- and flexible-length scan chains. Subsequently, we derive a formulation of an architecture-independent test time lower bound for SOCs and list the lower bound values for the 'ITC'02 SOC test benchmarks'. We present a novel architecture-independent heuristic algorithm that effectively optimizes the test architecture for a given SOC. The algorithm efficiently determines the number of TAMs and their widths, the assignment of modules to TAMs, and the wrapper design per module. We show how this algorithm can be used for optimizing both test bus and testrail architectures with serial and parallel test schedules. Experimental results for the 'ITC'02 SOC test benchmarks' show that, compared to previously published algorithms, we obtain comparable or better test times at negligible compute time.

Application of deterministic logic BIST on industrial circuits

Abstract: We present the application of a deterministic logic BIST scheme on state-of-the-art industrial circuits. Experimental results show that complete fault coverage can be achieved for industrial circuits up to 100 K gates with 10000 test patterns, at a total area cost for BIST hardware of typically 5%-15%. It is demonstrated that a tradeoff is possible between test quality, test time, and silicon area. In contrast to BIST schemes based on test point insertion no modifications of the circuit under test are required, complete fault efficiency is guaranteed, and the impact on the design process is minimized.