Bit line control circuit for a content addressable memory
View Patent ↗A bit line control circuit is coupled between a bit line of an associated Content Addressable Memory (CAM). Array and a supply voltage. The bit line control circuit adjusts the charge current for the bit line in response to a bit line control signal. For some embodiments, the bit line control circuit includes a dynamic component and a static component to control the bit line.
1. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
a bit line control circuit coupled to the bit line and having an input to receive a control signal, wherein the bit line control circuit minimizes a bit line charge current during a sensing phase of a read operation.
2. The CAM array of claim 1 , wherein the bit line control circuit adjusts the charge current for the bit line in response to the control signal.
3. The CAM array of claim 1 , wherein the bit line control circuit maximizes the bit line charge current during a recovery phase of the read operation.
4. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
a bit line control circuit coupled to the bit line and having an input to receive a control signal, wherein the bit line control circuit minimizes a bit line charge current when there is a compare operation and maximizes the bit line charge current when there is not a compare operation.
5. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
a bit line control circuit coupled to the bit line and having an input to receive a control signal, wherein the bit line control circuit comprises a dynamic charge circuit coupled between the bit line and a supply voltage, the dynamic charge circuit having an input responsive to the control signal.
6. The CAM array of claim 5 , wherein the bit line control circuit further comprises:
a static charge circuit coupled between the bit line and the supply voltage.
7. The CAM array of claim 6 , wherein:
the static charge circuit provides a relatively small bit line charge current; and
the dynamic charge circuit selectively provides a relatively large bit line charge current in response to the control signal.
8. The CAM array of claim 6 , wherein:
the static charge circuit comprises a first transistor coupled between the bit line and the supply voltage and having a gate coupled to a predetermined voltage; and
the dynamic charge circuit comprises a second transistor coupled between the bit line and the supply voltage and having a gate to receive the control signal.
9. The CAM array of claim 8 , wherein the first and second transistors comprise PMOS transistors.
10. The CAM array of claim 8 , wherein the second transistor is 50% stronger than the first transistor.
11. The CAM array of claim 5 , wherein the dynamic charge circuit is enabled if there is not a compare operation.
12. The CAM array of claim 5 , wherein the dynamic charge circuit is disabled during a compare operation.
13. The CAM array of claim 5 , wherein the dynamic charge circuit is disabled during a sensing phase of a read operation.
14. The CAM array of claim 5 , wherein the dynamic charge circuit is enabled during a recovery phase of a read operation.
15. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
means for adjusting a charge current for the bit line in response to a control signal, wherein the means for adjusting comprises:
means for providing a relatively small bit line charge current during a sensing phase of a read operation; and
means for providing a relatively large bit line charge current during a recovery phase of the read operation.
16. The CAM array of claim 15 , wherein the means for providing a relatively large bit line charge current is disabled during the sensing phase of the read operation.
17. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
means for adjusting a charge current for the bit line in response to a control signal, wherein the means for adjusting comprises:
means for providing a relatively small bit line charge current when there is a compare operation; and
means for providing a relatively large bit line charge current when there is not a compare operation.
18. The CAM array of claim 17 , wherein the means for providing a relatively large bit line charge current is disabled during the compare operation.
19. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
means for adjusting a charge current for the bit line in response to a control signal, wherein the means for adjusting comprises:
a first transistor coupled between the bit line and a supply voltage, and having a gate coupled to a predetermined voltage; and
a second transistor coupled between the bit line and the supply voltage, and having a gate responsive to the control signal.
20. The CAM array of claim 19 , wherein the first and second transistors comprise PMOS transistors.
21. A content addressable memory (CAM) array having any number of columns, each of the columns comprising:
a plurality of CAM cells coupled to a bit line; and
means for adjusting a charge current for the bit line in response to a control signal, wherein the means for adjusting comprises:
a static charge circuit coupled between the bit line and a supply voltage terminal; and
a dynamic charge circuit coupled between the bit line and the supply voltage terminal, and responsive to the control signal.
22. The CAM array of claim 21 , wherein the dynamic charge circuit has a drive strength 50% stronger than the static charge circuit.