Semiconductor device
AssigneeRenesas Electronics Corporation
InventorsYohei SAWADA, Masao MORIMOTO, Makoto YABUUCHI
Life of this patent
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Abstract
The plurality of CAM cells MC are configured to discriminate a match or mismatch between stored data stored in advance and search data. A match line is coupled to a plurality of CAM cells, and has a voltage level controlled based on discrimination results of the plurality of CAM cells. A first transistor and a second transistor are coupled in series between a common match output line and a predetermined power source. The first transistor is controlled to be turned ON or OFF based on a voltage level of the match line, and the second transistor is controlled to be turned ON or OFF by a search enabling signal asserted at the time of a search operation.
Claims13
A semiconductor device having a CAM (Content Addressable Memory) unit,
- wherein the CAM unit comprises:
- a plurality of CAM entries;
- a plurality of search lines provided so as to be common to the plurality of CAM entries and to which search data from outside the semiconductor device are input;
- and
- a common match output line provided so as to be common to the plurality of CAM entries,
- each of the plurality of CAM entries has:
- a plurality of CAM cells configured to discriminate a match or mismatch between stored data stored in advance and the search data;
- a match line coupled to the plurality of CAM cells, and having a voltage level controlled based on discrimination results of the plurality of CAM cells;
- and
- a first transistor and a second transistor coupled in series between the common match output line and a predetermined power source,
- the first transistor is controlled to be turned ON or OFF based on the voltage level of the match line, and
- the second transistor is controlled to be turned ON or OFF by a search enabling signal asserted at the time of a search operation.
A semiconductor device having a TCAM (Ternary Content Addressable Memory) unit,
- wherein the TCAM unit comprises:
- a plurality of TCAM entries;
- a plurality of search lines provided so as to be common to the plurality of TCAM entries and to which search data from outside the semiconductor device are input;
- and
- a common match output line provided so as to be common to the plurality of TCAM entries,
- each of the plurality of TCAM entries has:
- a dual-port type valid bit cell configured to store valid data representing validity or invalidity of its own TCAM entry, the dual-port type valid bit cell being accessible by a first word line or a second word line;
- a plurality of TCAM cells configured to discriminate a match or mismatch between stored data stored in advance and the search data;
- a match line coupled to the plurality of TCAM cells, and having a voltage level controlled based on discrimination results of the plurality of TCAM cells;
- a first transistor and a second transistor coupled in series between the common match output line and a predetermined power source;
- and
- a third transistor coupled in parallel to the second transistor,
- the first transistor is controlled to be turned ON or OFF based on the voltage level of the match line,
- the second transistor is controlled to be turned ON or OFF by a search enabling signal asserted at the time of a search operation, and
- at the time of the read operation, the third transistor is controlled to be turned ON or OFF by the first word line or the second word line
Dependencies are inferred from the claim text.