A low cost BIST methodology and associated novel test pattern generator

The area overhead and performance degradation associated with the hardware used to make a circuit testable using the conventional BILBO methodology can often be excessive. This paper presents a new BILBO-oriented methodology, called Built-In test for Balanced Structure (BIBS), that significantly reduces the number of BILBO registers used in creating a testable circuit, and thus decreases the area overhead and performance degradation. The concept of k-step functionally testable circuits is introduced. When the BIBS methodology is employed, circuits under test are guaranteed to be 1-step functionally testable and thus a high fault coverage can be achieved. A novel test pattern generator design to achieve 1-step functional testability for the BIBS TDM is presented