Testing content-addressable memories using functional fault models and march-like algorithms

Functional tests for content-addressable memories (CAM´s) are presented in this paper. In addition to several traditional functional fault models for RAM´s, we also consider the fault models based on physical defects, such as shorts between two circuit nodes and transistor stuck-on and stuck open faults. Accordingly, several functional fault models are proposed. In order to make our approach suited to various application-specific CAM´s, we propose tests which require only three fundamental types of operation (i.e., write, erase, and compare), and the test results can be observed entirely from the single-bit Hit output. A complete, compact test is also proposed, which has low complexity and is suitable for modern high-density and large-capacity CAMs-it requires only 2N+3w+2 compare operations and 8N write operations to cover the functional fault models discussed, where N is the number of words and w is the word length