Content addressable memory in which keys are embedded in comparators

摘要

A content addressable memory (CAM) system can include a comparator core in which all of the keys of the CAM are embedded in comparator blocks. A search key can be provided to each of the comparator blocks, which can compare the search key to its embedded key and determine whether the search key matches the embedded key. The comparator blocks can be organized into paged sets in the comparator core such that only one of the comparator blocks in each paged set is selected and compares its embedded key to the search key at any given time. The comparator block selected in each paged set can be incremented until the search key has been compared to the keys embedded in all of the comparator blocks of the comparator core.

主权项

1. A content addressable memory (CAM) system comprising:
a search key input configured to receive an N-bit search key; a comparator core configured to embed W N-bit embedded keys in W comparator blocks each configured to compare its embedded key to the N-bit search key, wherein each comparator block comprises M look up tables (LUTs) each programmed to embed an L-bit subset of the embedded key in the comparator block and having an L-bit input for an L-bit subset of the search key where M is greater than one and L is less than N, and wherein each comparator block outputs a match indication only if each L-bit subset of the search key matches each corresponding L-bit subset of the embedded key in the comparator block subject to any masked bits; and a location decoder connected to outputs of the comparator blocks and configured to identify a location in the comparator core of one of the embedded keys that matches the search key.