US 10,095,824 B1Granted

Systems and methods for symmetric H-tree construction with complicated routing blockages

AssigneeCadence Design Systems, Inc.

InventorsZhuo Li, Wen-Hao Liu, Charles Alpert, Brian Wilson

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Abstract

Disclosed herein are systems and methods to construct a symmetric clock-distribution H-tree in upper layers of an integrated circuit (IC), which may have complicated routing and/or placement blockages. The systems and methods disclosed herein may implement concomitant bottom-up wiring and top-down rewiring to achieve a clock-distribution tree symmetrically balanced across all of the hierarchical levels while respecting the complicated routing and/or placement blockages. Such symmetrically balanced clock-tree ensures that a clock-signal reaches all of the clock-sinks simultaneously or near simultaneously thereby minimizing clock-skew across the clock-sinks. The minimal skew symmetric clock-distribution H-tree may therefore be used for higher performance and high speed ICs.

Claims20

Dependent claims

A computer-implemented method comprising:

identifying, by a computer, a first record of a first clock-tree segment at a first location in an integrated circuit (IC) and a second record of a second clock-tree segment at a second location in the IC, wherein the second clock-tree segment is to be wired to the first clock-tree segment;
and
upon determining, by the computer, that a routing track is unavailable from a midpoint or approximate midpoint of the first clock-tree segment to the midpoint or approximate midpoint of the second clock-tree segment:
determining, by the computer, at least one of a first alternate location for the first clock-tree segment and a second alternate location for the second clock-tree segment such that a routing track is available to route a clock-signal wire from the midpoint or approximate midpoint of the first clock-tree segment to the midpoint or approximate midpoint of the second clock-tree segment;
updating, by the computer, location information in at least one of the first record of the first clock-tree segment, from the first location to the first alternate location and the second record of the second clock-tree segment from the second location to the second alternate location;
generating, by the computer, a record of a first clock-tree segment hierarchically above the first and second clock-tree segments, wherein the first clock-tree segment hierarchically above the first and second clock-tree segments includes the first clock-tree segment wired to the second clock-tree segment by a first clock-signal wire in the routing track and connecting the midpoints or approximate midpoints of the first and second clock-tree segments;
and
recursively updating, by the computer, a record of at least one clock-tree segment hierarchically below the first and second clock-tree segments based upon updating the location information in at least one of the first and second records.

5 more elements

A system for circuit design, the system comprising:

one or more computers comprising a non-transitory machine-readable media configured to store a plurality of records of a plurality of clock-tree segments forming a at least a portion of a clock-distribution tree in an integrated circuit (IC);
and
at least one computer of the one or more computers, the at least one computer coupled to the non-transitory machine readable media storing the plurality of records and comprising a processor configured to:
identify a first record of a first clock-tree segment at a first location in the IC and a second record of a second clock-tree segment at a second location in the IC and to be wired to the first clock-tree segment;
upon determining by the computer that a routing track is unavailable from a midpoint or approximate midpoint of the first clock-tree segment to the midpoint or approximate midpoint of the second clock-tree segment:
determine at least one of a first alternate location for the first clock-tree segment and a second alternate location for the second clock-tree segment such that a routing track is available to route a clock-signal wire from the midpoint or approximate midpoint of the first clock-tree segment to the midpoint or approximate midpoint of the second clock-tree segment;
update location information in at least one of the first record of the first clock-tree segment, from the first location to the first alternate location and the second record of the second clock-tree segment from the second location to the second alternate location;
generate a record of a first clock-tree segment hierarchically above the first and second clock-tree segments, wherein the first clock-tree segment hierarchically above the first and second clock-tree segments includes the first clock-tree segment wired to the second clock-tree segment by a first clock-signal wire in the routing track and connecting the midpoints or approximate midpoints of the first and second clock-tree segments;
and
recursively update a record of at least one clock-tree segment hierarchically below the first and second clock-tree segments based upon updating the location information in at least one of the first and second records.

7 more elements

Dependencies are inferred from the claim text.