Behavioral-structural testability modeling and synthesis for bist with applications to high-level synthesis
C. Papachristou, Mikhail Baklashov · 1997
The objective of this work was to develop another integrated Built-In-Self-Test (BIST) technique and its associated tools. The concept of BIST offers a paradigm shift over the conventional (external) form of manufacture testing, that scales extremely well with high level synthesis systems. This work presents a novel method for test synthesis with minimum or no insertion. The test synthesis is guided by two testability metrics which quantify the controllability and observability of behavioral variables and structural signals. The method is based on utilization of redundant register transfers in the datapath to produce a test behavior with better controllability and observability properties. This approach allows us to avoid unnecessary insertions of test structures in the data path. A special test scheme for conditional statements has been developed. It required some changes in controller which have been accommodated in the controller implementation. Our experiments showed improvements in fault coverage results along with modest hardware overhead. In this work, simulation and heuristic approaches have been explored as a basis for the testability metric computations. We introduced the notion of testability fidelity for bit-scale behaviors and structural datapaths and emulated the testability computations based on Monte Carlo simulation. To facilitate testability computations the internal design representation in terms of the CDFG has been developed as well as several graph traversal algorithms have been implemented. Tools supporting the testability computations are presented.