Self-Initializing Memory Elements

Test generation for sequential circuits is complicated by the fact that the initial internal state of a circuit, after power-up, cannot be predicted. This is commonly referred to as the initializability problem. In this paper, we present a new solution to the initializability problem—self-initializing memory elements (SIME’s). SIME’s are designed to initialize, at power-up, to a known state. The start-up environment of a memory element is analyzed in detail. This analysis is used to design several different types of SIME’s. Each of the designs meet different user requirements. We also discuss the application of SIME’s to the problem of test generation for sequential circuits. SIME’s have distinct advantages over on-chip reset signals. Compared to off-chip reset signals, they offer a different overhead-benefit trade-off. They may also be used in conjunction with other design for test techniques. In short, they provide a designer with additional flexibility during the design process.