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US6480994B1
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Balanced clock placement for integrated circuits containing megacells
Assignee: Bell Semiconductor LLC
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Filing: 2001-02-15
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Granted: 2002-11-12
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Expires: 2021-02-15
Abstract
Abstract A method of clock buffer placement for minimizing clock skew for an integrated circuit includes the steps of (a) finding an ideal location for a clock buffer on an integrated circuit that minimizes clock skew, (b) checking whether the ideal clock buffer location overlaps a megacell, and (c) finding a location for the clock buffer that is closest to the ideal clock buffer location and that does not overlap a megacell.
Inventors
- 👤 Alexander Tetelbaum
- 👤 Rajiv Kapur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:20
CPC Classifications
G; G06; G06F; G06F1/00; G06F1/04; G06F1/10; G06F30/00; G06F30/30; G06F30/39; G06F30/394
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
A method of clock buffer placement for minimizing clock skew in an integrated circuit having megacells that includes the steps of: (a) finding an ideal location for a clock buffer on an integrated circuit that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; and (c) finding a location for the clock buffer that is closest to the ideal clock buffer location and that does not overlap a megacell.
Claim 2
Independent Claim
74 words
A method of clock buffer placement for minimizing clock skew in an integrated circuit having megacells that includes the steps of: (a) finding an ideal location for a clock buffer on an integrated circuit that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; and (c) finding a location for the clock buffer that is closest to the ideal clock buffer location and that does not overlap a megacell.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein step (c) includes finding a set of megacells accessible by a common adjacent side to the megacell overlapped if the ideal clock buffer location overlaps a megacell.
Claim 4
Dependent Claim
19 words
The method of claim 2 wherein step (c) includes defining a megacell boundary that encloses the set of megacells.
Claim 5
Dependent Claim
34 words
The method of claim 3 wherein step (c) includes comparing each available location along the megacell boundary to find the location for the clock buffer that is closest to the ideal clock buffer location.
Claim 6
Independent Claim
184 words
A method of clock buffer placement for minimizing clock skew in an integrated circuit having megacells comprising the steps of: (a) finding an ideal clock buffer location on a clock tree that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; (c) finding a set of megacells that are accessible by a common adjacent side to an overlapped megacell; (d) defining a megacell boundary that encloses the set of megacells; (e) finding an initial location where the clock buffer may be placed without overlapping a megacell; (f) storing the initial location in memory; (g) finding the next available location where the clock buffer may be placed without overlapping a megacell; (h) checking whether the next available location is closer to the ideal clock buffer location than the location stored in memory; (i) replacing the location stored in memory with the next available location found in step (g); (j) checking whether every available location has been compared with the ideal clock buffer location; (k) retrieving the location stored in memory; and (l) placing the clock buffer at the retrieved location.
Claim 7
Independent Claim
184 words
A method of clock buffer placement for minimizing clock skew in an integrated circuit having megacells comprising the steps of: (a) finding an ideal clock buffer location on a clock tree that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; (c) finding a set of megacells that are accessible by a common adjacent side to an overlapped megacell; (d) defining a megacell boundary that encloses the set of megacells; (e) finding an initial location where the clock buffer may be placed without overlapping a megacell; (f) storing the initial location in memory; (g) finding the next available location where the clock buffer may be placed without overlapping a megacell; (h) checking whether the next available location is closer to the ideal clock buffer location than the location stored in memory; (i) replacing the location stored in memory with the next available location found in step (g); (j) checking whether every available location has been compared with the ideal clock buffer location; (k) retrieving the location stored in memory; and (l) placing the clock buffer at the retrieved location.
Claim 8
Dependent Claim
202 words
A computer program product comprising: a medium for embodying a computer program for input to a computer; and a computer program embodied in the medium for causing the computer to perform at least one of the following functions: (a) finding an ideal clock buffer location on a clock tree that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; (c) finding a set of megacells that are accessible by a common adjacent side to an overlapped megacell; (d) defining a megacell boundary that encloses the set of megacells; (e) finding an initial location where the clock buffer may be placed without overlapping a megacell; (f) storing the initial location in memory; (g) finding the next available location where the clock buffer may be placed without overlapping a megacell; (h) checking whether the next available location is closer to the ideal clock buffer location than the location stored in memory; (i) replacing the location stored in memory with the next available location found in step (g); (j) checking whether every available location has been compared with the ideal clock buffer location; (k) retrieving the location stored in memory; and (l) placing the clock buffer at the retrieved location.
Claim 9
Dependent Claim
202 words
A computer program product comprising: a medium for embodying a computer program for input to a computer; and a computer program embodied in the medium for causing the computer to perform at least one of the following functions: (a) finding an ideal clock buffer location on a clock tree that minimizes clock skew; (b) checking whether the ideal clock buffer location overlaps a megacell; (c) finding a set of megacells that are accessible by a common adjacent side to an overlapped megacell; (d) defining a megacell boundary that encloses the set of megacells; (e) finding an initial location where the clock buffer may be placed without overlapping a megacell; (f) storing the initial location in memory; (g) finding the next available location where the clock buffer may be placed without overlapping a megacell; (h) checking whether the next available location is closer to the ideal clock buffer location than the location stored in memory; (i) replacing the location stored in memory with the next available location found in step (g); (j) checking whether every available location has been compared with the ideal clock buffer location; (k) retrieving the location stored in memory; and (l) placing the clock buffer at the retrieved location.
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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) | 2005-11-11 | 2006-05-13 | 2006-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-11-11 | 2010-05-13 | 2010-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-11-11 | 2014-05-13 | 2014-11-12 | $7700.00 | Window Closed / Lapsed |