Reducing dynamic clock skew and/or slew in an electronic circuit

Patent metadata

Field	Value
Publication number	US-9754063-B2
Application number	US-201514941847-A
Country	US
Kind code	B2
Filing date	Nov 16, 2015
Priority date	Nov 17, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

Reducing dynamic clock skew and/or slew in an electronic circuit is provided by: referencing a layout database and/or netlist of a design for the electronic circuit; identifying a set of neighboring buffer pairs with active buffers and adjacent sub-meshes, which are connected by a shorting bar; for each neighboring buffer pair of the set: placing a dummy buffer for each of their active buffers in the adjacent sub-meshes close to the active buffers; routing an input of a first dummy buffer located in a first sub-mesh to an output of an active buffer in a second sub-mesh; routing an input of a second dummy buffer located in the second sub-mesh to an output of an active buffer in the first sub-mesh; and connecting inputs of the first and second dummy buffers to the shorting bar.

First claim

What is claimed is:

1. A method of reducing dynamic clock skew and/or slew in a digital electronic circuit caused by varying physical parameters, the method comprising:
referencing a layout database and/or a netlist of a design for the digital electronic circuit before its manufacturing, the design comprising a clock mesh having adjacent sub-meshes driven by at least partially disjoint clock trees and connecting outputs of leaf level drivers in the design, the clock trees being driven by a common root tree, wherein clock trees of adjacent sub-meshes are connected at a given level (L(n)) by a shorting bar (SB), and wherein the sub-meshes contain dummy buffers at a level (L(m)) equal or higher than the shorting bar level (L(n));
modifying the digital electronic circuit design to reduce dynamic clock skew and/or slew, including:
identifying a set of neighboring buffer pairs (BP(i)) each comprising active buffers in adjacent sub-meshes, which are connected by the shorting bar (SB);
for each neighboring buffer pair (BP(i)) of the set:
placing a dummy buffer for each of their active buffers in the adjacent sub-meshes close to the active buffers;
routing an input of a first dummy buffer located in a first sub-mesh to an output of an active buffer in a second sub-mesh;
routing an input of a second dummy buffer located in the second sub-mesh to an output of an active buffer in the first sub-mesh; and
connecting inputs of the first and second dummy buffers to the shorting bar (SB).

2. The method of claim 1 , further comprising searching for dummy buffers in the adjacent sub-meshes starting with the shorting bar level (L(n)).

3. The method of claim 2 , wherein in case the level (L(m)) of the found dummy buffers equals the shorting bar level (L(n)), the found dummy buffers are placed close to the active buffers in the adjacent sub-meshes.

4. The method of claim 2 , wherein in case the level (L(m)) of the found dummy buffers is higher than the shorting bar level (L(n)), (L(m)>L(n)), the found dummy buffers are changed to active buffers.

5. The method of claim 4 , wherein in case the level (L(m)) of the found dummy buffers is higher than a certain level (L(n+1)), (L(m)>L(n+1)), additional buffer stages are inserted, placed and routed, wherein additional dummy buffers are added to the shorting bar level (L(n)).

6. The method of claim 5 , wherein in case the level (L(m)) of the found dummy buffers equals the level (L(n+1)), (L(m)=L(n+1)), additional dummy buffers are added to the shorting bar level (L(n)).

7. The method of claim 6 , wherein the additional dummy buffers are placed close to the active buffers in the adjacent sub-meshes.

8. A system to reduce dynamic clock skew and/or slew in a digital electronic circuit caused by varying physical parameters, the system comprising:
a memory; and
a processing device communicatively coupled to the memory, wherein the system performs a method comprising:
referencing a layout database and/or a netlist of a design for the digital electronic circuit before its manufacturing, the design comprising a clock mesh having adjacent sub-meshes driven by at least partially disjoint clock trees and connecting outputs of leaf level drivers in the design, the clock trees being driven by a common root tree, wherein clock trees of adjacent sub-meshes are connected at a given level (L(n)) by a shorting bar (SB), and wherein the sub-meshes contain dummy buffers at a level (L(m)) equal or higher than the shorting bar level (L(n));
modifying the digital electronic circuit design to reduce dynamic clock skew and/or slew, including:
identifying a set of neighboring buffer pairs (BP(i)) each comprising active buffers in adjacent sub-meshes, which are connected by the shorting bar (SB);
for each neighboring buffer pair (BP(i)) of the set:
placing a dummy buffer for each of their active buffers in the adjacent sub-meshes close to the active buffers;
routing an input of a first dummy buffer located in a first sub-mesh to an output of an active buffer in a second sub-mesh;
routing an input of a second dummy buffer located in the second sub-mesh to an output of an active buffer in the first sub-mesh; and
connecting inputs of the first and second dummy buffers to the shorting bar (SB).

9. The system of claim 8 , further comprising searching for dummy buffers in the adjacent sub-meshes starting with the shorting bar level (L(n)).

10. The system of claim 9 , wherein in case the level (L(m)) of the found dummy buffers (D) equals the shorting bar level (L(n)), the found dummy buffers are placed close to the active buffers in the adjacent sub-meshes.

11. The system of claim 9 , wherein in case the level (L(m)) of the found dummy buffers is higher than the shorting bar level (L(n)), (L(m)>L(n)), the found dummy buffers are changed to active buffers.

12. The system of claim 11 , wherein in case the level (L(m)) of the found dummy buffers is higher than a certain level (L(n+1)), (L(m)>L(n+1)), additional buffer stages are inserted, placed and routed, wherein additional dummy buffers are added to the shorting bar level (L(n)).

13. The system of claim 12 , wherein in case the level (L(m)) of the found dummy buffers equals the level (L(n+1)), (L(m)=L(n+1)), additional dummy buffers are added to the shorting bar level (L(n)).

14. The system of claim 13 , wherein the additional dummy buffers are placed close to the active buffers in the adjacent sub-meshes.

15. A computer program product for reducing dynamic clock skew and/or slew in a digital electronic circuit caused by varying physical parameters, the computer program product comprising:
a computer readable storage medium having computer readable program instructions embodied therewith, the computer readable program instructions being executable by a processor to perform a method comprising:
referencing a layout database and/or a netlist of a design for the digital electronic circuit before its manufacturing, the design comprising a clock mesh having adjacent sub-meshes driven by at least partially disjoint clock trees and connecting outputs of leaf level drivers in the design, the clock trees being driven by a common root tree, wherein clock trees of adjacent sub-meshes are connected at a given level (L(n)) by a shorting bar (SB), and wherein the sub-meshes contain dummy buffers at a level (L(m)) equal or higher than the shorting bar level (L(n));
modifying the digital electronic circuit design to reduce dynamic clock skew and/or slew, including:
identifying a set of neighboring buffer pairs (BP(i)) each comprising active buffers in adjacent sub-meshes, which are connected by the shorting bar (SB);
for each neighboring buffer pair (BP(i)) of the set:
placing a dummy buffer for each of their active buffers in the adjacent sub-meshes close to the active buffers;
routing an input of a first dummy buffer located in a first sub-mesh to an output of an active buffer in a second sub-mesh;
routing an input of a second dummy buffer located in the second sub-mesh to an output of an active buffer in the first sub-mesh; and
connecting inputs of the first and second dummy buffers to the shorting bar (SB).

16. The computer program product of claim 15 , further comprising searching for dummy buffers in the adjacent sub-meshes starting with the shorting bar level (L(n)).

17. The computer program product of claim 16 , wherein in case the level (L(m)) of the found dummy buffers equals the shorting bar level (L(n)), the found dummy buffers are placed close to the active buffers in the adjacent sub-meshes.

Assignees

• IBM

Inventors

• Arp Andreas
• Cilek Fatih
• Hutzl Guenther
• Koch Michael
• Ringe Matthias

Classifications

• G06F30/396 Primary

  Clock trees · CPC title

• G06F30/39

  Circuit design at the physical level (physical level design for reconfigurable circuits G06F30/347) · CPC title

• G06F30/392

  Floor-planning or layout, e.g. partitioning or placement · CPC title

• G06F30/394

  Routing (G06F30/396 takes precedence) · CPC title

• G06F1/10 Primary

  Distribution of clock signals {, e.g. skew} · CPC title