US6101115A
Expired / Lapsed
US
⏱️ 0.0 years remaining
CAM match line precharge
Assignee: Cisco Technology Inc
•
Filing: 1998-08-07
•
Granted: 2000-08-08
•
Expires: 2018-08-07
Abstract
Abstract The invention provides a method and system for improved CAM match line precharge, in which the amount of power consumed by match line precharge and discharge is significantly reduced. An independent match precharge voltage is introduced to the CAM, which is used to separately precharge the match line and is available for use by comparison circuits to attempt to match the input tag. The match precharge voltage is selected so as to reduce the relative power consumption for match line precharge and discharge by a factor of about five. Optionally, sense amplifiers in the comparison circuits are disposed so as to compare each discharged match line with the match precharge voltage itself.
Inventors
- 👤 Mark Ross
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:30
CPC Classifications
G; G11; G11C; G11C15/00; G11C15/04
Claims Analysis
Total Claims: 45
Claim 1
Independent Claim
59 words
An independent match-line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; wherein said selected match precharge voltage provide for relatively lower power consumption of said memory when said selected match precharge voltage is substantially less than said operating voltage.
Claim 2
Dependent Claim
59 words
An independent match-line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; wherein said selected match precharge voltage provide for relatively lower power consumption of said memory when said selected match precharge voltage is substantially less than said operating voltage.
Claim 3
Dependent Claim
21 words
A memory as in claim 1, wherein said memory includes a mask value for at least some lines of said memory.
Claim 4
Dependent Claim
15 words
A memory as in claim 1, wherein said memory includes a ternary content addressable memory.
Claim 5
Dependent Claim
29 words
A memory as in claim 1, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater than about 2.00 volts.
Claim 6
Dependent Claim
30 words
A memory as in claim 1, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
Claim 7
Dependent Claim
16 words
A memory as in claim 1, wherein said selected match precharge voltage is about 1.8 volts.
Claim 8
Dependent Claim
16 words
A memory as in claim 1, wherein said selected match precharge voltage is about 1.0 volt.
Claim 9
Dependent Claim
18 words
A memory as in claim 1, wherein said selected match precharge voltage is less than about 2.0 volts.
Claim 10
Dependent Claim
28 words
A memory as in claim 1, including a sense amplifier; wherein said selected precharge voltage provides a noise margin substantially above a switching point for said sense amplifier.
Claim 11
Dependent Claim
60 words
An independent match line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; a set of sense amplifiers each coupled to at least one match line of said memory, each said sense amplifier being responsive to said selected match precharge voltage.
Claim 12
Dependent Claim
60 words
An independent match line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; a set of sense amplifiers each coupled to at least one match line of said memory, each said sense amplifier being responsive to said selected match precharge voltage.
Claim 13
Dependent Claim
21 words
A memory as in claim 10, wherein said memory includes a mask value for at least some lines of said memory.
Claim 14
Dependent Claim
15 words
A memory as in claim 10, wherein said memory includes a ternary content addressable memory.
Claim 15
Dependent Claim
27 words
A memory as in claim 10, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater 2.0 volts.
Claim 16
Dependent Claim
30 words
A memory as in claim 10, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
Claim 17
Dependent Claim
16 words
A memory as in claim 10, wherein said selected match precharge voltage is about 1.8 volts.
Claim 18
Dependent Claim
16 words
A memory as in claim 10, wherein said selected match precharge voltage is about 1.0 volt.
Claim 19
Dependent Claim
18 words
A memory as in claim 10, wherein said selected match precharge voltage is less than about 2.0 volts.
Claim 20
Dependent Claim
28 words
A memory as in claim 10, including a sense amplifier; wherein said selected precharge voltage provides a noise margin substantially above a switching point for said sense amplifier.
Claim 21
Dependent Claim
87 words
An independent match-line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; a set of sense amplifiers each coupled to at least one match line of said memory, each said sense amplifier being responsive to said selected match precharge voltage; wherein said selected match precharge voltage provides for relatively lower power consumption of said memory when said selected match precharge voltage is substantially less than said operating voltage.
Claim 22
Dependent Claim
87 words
An independent match-line precharge voltage within a content addressable memory, including an input port disposed for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; a set of sense amplifiers each coupled to at least one match line of said memory, each said sense amplifier being responsive to said selected match precharge voltage; wherein said selected match precharge voltage provides for relatively lower power consumption of said memory when said selected match precharge voltage is substantially less than said operating voltage.
Claim 23
Dependent Claim
21 words
A memory as in claim 19, wherein said memory includes a mask value for at least some lines of said memory.
Claim 24
Dependent Claim
15 words
A memory as in claim 19, wherein said memory includes a ternary content addressable memory.
Claim 25
Dependent Claim
29 words
A memory as in claim 19, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater than about 2.0 volts.
Claim 26
Dependent Claim
30 words
A memory as in claim 19, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
Claim 27
Dependent Claim
16 words
A memory as in claim 19, wherein said selected match precharge voltage is about 1.8 volts.
Claim 28
Dependent Claim
16 words
A memory as in claim 19, wherein said selected match precharge voltage is about 1.0 volt.
Claim 29
Dependent Claim
18 words
A memory as in claim 19, wherein said selected match precharge voltage is less than about 2.0 volts.
Claim 30
Dependent Claim
26 words
A memory as in claim 19, wherein said selected precharge voltage provides a noise margin substantially above a switching point for said set of sense amplifiers.
Claim 31
Independent Claim
58 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and consuming relatively lower power during operating of said memory responsive to said selected match precharge voltage, when said selected match precharge voltage is substantially less than said operating voltage.
Claim 32
Independent Claim
58 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and consuming relatively lower power during operating of said memory responsive to said selected match precharge voltage, when said selected match precharge voltage is substantially less than said operating voltage.
Claim 33
Dependent Claim
28 words
A method as in claim 28, including steps for matching, for at least some lines of said memory, an input value for said memory against a mask value.
Claim 34
Dependent Claim
29 words
A method as in claim 28, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater than about 2.0 volts.
Claim 35
Dependent Claim
30 words
A method as in claim 28, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
Claim 36
Independent Claim
44 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and matching at least one match line of said memory responsive to selected match precharge voltage.
Claim 37
Independent Claim
44 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and matching at least one match line of said memory responsive to selected match precharge voltage.
Claim 38
Dependent Claim
28 words
A method as in claim 32, including steps for matching, for at least some lines of said memory, an input value for said memory against a mask value.
Claim 39
Dependent Claim
29 words
A method as in claim 32, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater than about 2.0 volts.
Claim 40
Dependent Claim
30 words
A method as in claim 32, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
Claim 41
Independent Claim
73 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and matching at least one match line of said memory responsive to selected match precharge voltage; consuming relatively lower power during operating of said memory responsive to said selected match precharge voltage, when said selected match precharge voltage is substantially less than said operating voltage.
Claim 42
Independent Claim
73 words
A method of operating a content addressable memory, said method including steps for receiving a selected match precharge voltage substantially independent of an operating voltage of said memory; and matching at least one match line of said memory responsive to selected match precharge voltage; consuming relatively lower power during operating of said memory responsive to said selected match precharge voltage, when said selected match precharge voltage is substantially less than said operating voltage.
Claim 43
Dependent Claim
28 words
A method as in claim 36, including steps for matching, for at least some lines of said memory, an input value for said memory against a mask value.
Claim 44
Dependent Claim
27 words
A method as in claim 36, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage greater 2.0 volts.
Claim 45
Dependent Claim
30 words
A method as in claim 36, wherein said power consumption is between about 20% to about 50% of that for a match precharge voltage substantially equal to said operating voltage.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-08-08 | 2004-02-07 | 2004-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-08-08 | 2008-02-07 | 2008-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-08-08 | 2012-02-07 | 2012-08-08 | $7700.00 | Window Closed / Lapsed |