A Digital Polarity Correlator with Built-in Self Test and Self Repair

Correlation techniques are widely used in communications, instrumentation, computers, telemetry, and other signal processing systems to detect a desired signal in the presence of noise, to recognize patterns, and to measure time delays. With the development of VLSI, correlation can be performed efficiently with a minimal number of components. The correlator chip presented in this article consists of a linear cascade of identical elements; failure of any one element causes complete chip failure. Therefore, we devised a self-test and self-repair structure to automatically bypass faulty stages. The overhead for self test and self repair was approximately six percent of the chip area. The results of functional testing of the first batch of processed chips demonstrated a nine-to-one yield enhancement and an exhaustive functional test time of less than 150 milliseconds. The self-repair mechanism provides high in-service reliability.