A method and apparatus are described for the filtering of a common input string to generate various filtered comparand strings. The filtering of a common input string enables concurrent lookups in different tables to be performed on multiple filtered comparands by different CAM devices (or different blocks within a CAM device), to compare the data in the filtered comparand strings with data stored in its associative memory. By performing multiple lookups in parallel, rather than sequentially, packet throughput in a CAM may be significantly increased.