A self-testing reconfigurable CAM

Abstract

The authors describe a 2- mu m CMOS reconfigurable content addressable memory (RCAM), organized as 256 words by 64 b, that can be written, searched, or read with 100-ns cycle time. Designed for general high-speed table lookup applications, the RCAM has self-test and reconfiguration features to simplify testing and improve yield. In test mode the RCAM tests the whole memory array in under 300 clock cycles and automatically reconfigures itself to correct any hard errors it finds, greatly enhancing the chip yield. As an example, the authors describe the application of the RCAM to address translation. Compared to RAM-based address translation, using the RCAM increases speed and reduces complexity. Also, the RCAM's storage reclamation feature simplifies system storage management by allowing old entries that have not been accessed recently to be freed for reuse.