Patent ID: 7054995

Claim:
A content addressable memory (CAM) system for holding entries and receiving a search input that includes a key, the CAM system comprising: a series of CAM banks configured according to a corresponding series of link-control signals to form a CAM module wherein the link-control signal is asserted for all but the first CAM bank or only the last CAM bank in the series, each CAM bank including: i) a CAM array having rows, each row configured to hold a field from one of the entries, to receive a corresponding field from the key, to determine if the entry field matches the key field , and, if so, to assert a field-match signal; and ii) a control circuit configured to receive the field match signal for each row, a match-in signal corresponding to each row, and the link-control signal corresponding to the CAM bank, and to generate based on these a match-out signal for each row; wherein the match-in signals received by the CAM banks are the match-out signals generated by the corresponding rows within any preceding CAM bank in the series; wherein, when the link-control signal is being asserted for all but the first CAM bank in the series: if the link-control signal is not asserted, the match-out signal generated for each row is then the field-match signal of that row, and if the link-control signal is asserted, the match-out signal generated for each row is then asserted only if both the match-in signal and the field-match signal of that row are asserted; and wherein, when the link-control signal is being asserted for only the last CAM bank in the series: if the link-control signal is not asserted, the match-out signal generated for each row is then asserted only if both the match-in signal and the field-match signal of that row are asserted, and if the link-control signal is asserted, the match-out signal generated for each row is then asserted.