System and method for clock optimization to achieve timing signoff in an electronic circuit and electronic design automation tool incorporating the same

1. A system for clock optimization to achieve timing signoff in an electronic circuit, comprising:

a clock cell identifier/sorter configured to identify at least some clock cells in a clock network associated with an electronic circuit design and sort said at least some clock cells according to breadth in an order from a broader breadth to a narrower breadth, wherein breadth of a clock cell of said at least some clock cells is a number of data paths of circuit elements driven by said clock cell of said clock network;

a slack analyzer associated with said clock cell identifier/sorter and configured to process said at least some clock cell in said order by identifying flops in said data paths that are downstream of said at least some clock cells and determining a worst setup and hold timing slack thereof; and

a clock cell delay adjuster associated with said slack analyzer and configured to adjust delays of said at least some clock cells subject to said worst setup and hold timing slack.

2. The system as recited in claim 1 wherein said slack analyzer is further configured to determine a worst slack on input data pins on said flops and said clock cell delay adjuster is further configured to adjust said delays subject to said worst slack.

3. The system as recited in claim 2 wherein said slack analyzer is further configured to exclude paths containing both identified transmitting and receiving flops.

4. The system as recited in claim 1 wherein said system is embodied in a timing signoff tool included in an electronic design automation tool, comprising:

a design tool configured to produce a register transfer logic representation of an electronic circuit; and

a layout tool configured to transform said register transfer logic representation into a physical layout of cells and interconnects and implement an engineering change order file with respect thereto.

5. The system as recited in claim 1 wherein said clock cell delay adjuster is further configured to cooperate with a cell library to carry out at least one of:

substituting a faster clock cell,

substituting a slower clock cell, and

adding a further clock cell.

6. The system as recited in claim 5 wherein said faster clock cell and said slower clock cell have identical footprints.

7. The system as recited in claim 1 wherein said slack analyzer and said clock cell delay adjuster are invoked multiple times to reach timing signoff.

8. A method of clock optimization to achieve timing signoff in an electronic circuit, comprising:

identifying at least some clock cells in a clock network associated with an electronic circuit design;

sorting said at least some clock cells according to breadth in an order of a broader breadth to a narrower breadth, wherein breadth of a clock cell of said at least some clock cells is a number of data paths of said clock network that include said clock cell; and

processing said at least some clock cells in said order, including:

identifying flops in said data paths that are downstream of said at least some clock cells;

determining a worst setup and hold timing slack of said flops; and

adjusting delays of said at least some clock cells subject to said worst setup and hold timing slack, wherein said determining and said adjusting are performed by a processor.

9. The method as recited in claim 8 further comprising:

determining a worst slack on input data pins on said flops; and

adjusting said delays subject to said worst slack.

10. The method as recited in claim 9 further comprising excluding paths containing both identified transmitting and receiving flops.

11. The method as recited in claim 8 wherein said method is carried out in a timing signoff tool included in an electronic design automation tool that further performs:

producing a register transfer logic representation of an electronic circuit;

transforming said register transfer logic representation into a physical layout of cells and interconnects; and

implementing an engineering change order file with respect to said physical layout.

12. The method as recited in claim 8 further comprising employing a cell library to carry out at least one of:

substituting a faster clock cell,

substituting a slower clock cell, and

adding a further clock cell.

13. The method as recited in claim 12 wherein said faster clock cell and said slower clock cell have identical footprints.

14. The method as recited in claim 8 further comprising carrying out said determining and said adjusting multiple times to reach timing signoff.

15. An electronic design automation tool, comprising:

a signoff analysis tool configured to perform a timing signoff and including:

a clock cell identifier/sorter configured to identify at least some clock cells in a clock network associated with an integrated circuit design and sort said at least some clock cells according to breadth in an order of a broader breadth to a narrower breadth, wherein breadth of a clock cell of said at least some clock cells is a number of data paths of said clock network that include said clock cell,

a slack analyzer associated with said clock cell identifier/sorter and configured to process said at least some clock cells in said order by identifying identify flops in said data paths that are downstream of said at least some clock cells, determining a worst setup and hold timing slack thereof and determining a worst slack on input data pins on said flops,

a clock cell delay adjuster associated with said slack analyzer and configured to adjust delays of said at least some clock cells subject to said worst setup and hold timing slack and said worst slack; and

an engineering change order generator associated with said clock cell delay adjuster and configured to transform an output thereof into an engineering change order file.

16. The electronic design automation tool as recited in claim 15 wherein said slack analyzer is further configured to exclude paths containing both identified transmitting and receiving flops.

17. The electronic design automation tool as recited in claim 15 further comprising:

a design tool configured to produce a register transfer logic representation of an electronic circuit; and

a layout tool configured to transform said register transfer logic representation into a physical layout of cells and interconnects and implement said engineering change order file with respect thereto.

18. The electronic design automation tool as recited in claim 15 wherein said clock cell delay adjuster is further configured to cooperate with a cell library to carry out at least one of:

substituting a faster clock cell,

substituting a slower clock cell, and

adding a further clock cell.

19. The electronic design automation tool as recited in claim 18 wherein said faster clock cell and said slower clock cell have identical footprints.

20. The electronic design automation tool as recited in claim 15 wherein said slack analyzer and said clock cell delay adjuster are invoked multiple times to reach timing signoff.