System and method for reducing power consumption in a content-addressable memory
View Patent ↗According to one disclosed embodiment, a content-addressable memory (CAM) system configured for reduced power consumption includes a sensing circuit utilized to apply a sense voltage to a matchline of the CAM system, a valid bit cell coupled to the matchline, and a power cut-off circuit configured to isolate the sense voltage from the matchline when an invalid validity state is stored in the valid bit cell, thereby reducing power consumption by the CAM system. In one embodiment, the power cut-off circuit isolates the sense voltage from the matchline by decoupling the sensing circuit from a control signal when an invalid validity state is stored in the valid bit cell.
1. A content-addressable memory (CAM) system configured for reduced power consumption, said CAM system comprising:
a sensing circuit to apply a sense voltage to a matchline of said CAM system;
a valid bit cell coupled between said matchline and a power cut-off circuit;
said power cut-off circuit configured to isolate said sense voltage from said matchline when an invalid validity state is stored in said valid bit cell, thereby reducing power consumption in said CAM system.
2. The CAM system of claim 1 , wherein said power cut-off circuit isolates said sense voltage from said matchline by decoupling said sensing circuit from a control signal when said invalid validity state is stored in said valid bit cell.
3. The CAM system of claim 1 , wherein said power cut-off circuit isolates said sense voltage from said matchline by forcing said sensing circuit to decouple said sense voltage from said matchline when said invalid validity state is stored in said valid bit cell.
4. The CAM system of claim 1 , further comprising:
a switching circuit coupling said valid bit cell to said matchline;
said switching circuit configured to apply a validity voltage different from said sense voltage to said matchline when said invalid validity state is stored in said valid bit cell.
5. The CAM system of claim 1 , wherein said power cut-off circuit comprises an NMOS transistor and a PMOS transistor.
6. The CAM system of claim 1 , wherein said power cut-off circuit comprises a transmission gate and a PMOS transistor.
7. The CAM system of claim 1 , wherein said power cut-off circuit comprises a single PMOS transistor.
8. The CAM system of claim 1 , wherein said matchline is coupled to one segment of a full entry of said CAM system.
9. The CAM system of claim 1 , further comprising:
a row block of one or more full entries of said CAM system;
wherein said valid bit cell is coupled to matchlines of said row block, and wherein said power cut-off circuit is configured to isolate one or more sense voltages from said matchlines of said row block.
10. The CAM system of claim 1 , further comprising:
a row block of one or more segments of full entries of said CAM system;
wherein said valid bit cell is coupled to matchlines of said row block, and wherein said power cut-off circuit is configured to isolate one or more sense voltages from said matchlines of said row block.
11. A method for reducing power consumption by a content-addressable memory (CAM) system, said method comprising:
designating an entry in said CAM system as invalid;
storing an invalid validity state in a valid bit cell coupled to a matchline of said entry;
isolating a sense voltage from said matchline by a power cut-off circuit, thereby reducing power consumption in said CAM system;
wherein said valid bit cell is coupled between said matchline and said power cut-off circuit.
12. The method of claim 11 , wherein said isolating comprises decoupling a sensing circuit from a control signal when said invalid validity state is stored in said valid bit cell.
13. The method of claim 11 , wherein said isolating comprises forcing a sensing circuit to decouple said sense voltage from said matchline when said invalid validity state is stored in said valid bit cell.
14. The method of claim 11 , further comprising:
applying a validity voltage different from said sense voltage to said matchline when said invalid validity state is stored in said valid bit cell.
15. The method of claim 11 , wherein said CAM system comprises a binary CAM system.
16. The method of claim 11 , wherein Said CAM system - comprises a ternary CAM system.
17. The method of claim 11 , wherein said entry comprises one full entry of said CAM system.
18. The method of claim 11 , wherein said entry comprises one segment of a full entry of said CAM system.
19. The method of claim 11 , further comprising:
designating a row block of one or more full entries in said CAM system as invalid, wherein said valid bit cell is coupled to matchlines of said row block;
isolating one or more sense voltages from said matchlines when said invalid validity state is stored in said valid bit cell.
20. The method of claim 11 , further comprising:
designating a row block of one or more segments of full entries in said CAM system as invalid, wherein said valid bit cell is coupled to matchlines of said row block;
isolating one or more sense voltages from said matchlines when said invalid validity state is stored in said valid bit cell.