Method and apparatus for sizing buffers to provide minimal skew
First Claim
1. A method of generating buffer data for use in selecting suitable buffer types for placement at given locations in a signal distribution network during the design of a microprocessor, the suitable buffer types being selected to minimize skew in the signal distribution network, the method comprising the following steps:
- providing a collection of buffer types available for placement at given locations within a first stage of the signal distribution network;
providing a skew budget for signal propagation between the first stage and a next adjacent stage of said signal distribution network;
for said first stage of the signal distribution network, providing a range of incrementally varying values of at least one feature affecting skew, at least one of said incrementally varying values depending on at least one of said given locations within said first stage; and
automatically selecting, for each of said incrementally varying values, one or more suitable buffer types from among the collection of buffer types, which suitable buffer types are selected to meet the skew budget.
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Accused Products
Abstract
Disclosed is a system for automatically generating tables of buffer data which can be used during integrated circuit design to select appropriate buffers for signal distribution networks. The generated buffer data may be used by automated place and route systems to generate signal distribution networks having minimal skew. In the table, incrementally varying network features or criteria are provided (in the form of a table or list for example). Examples of such features include the length of a line connecting an L4 buffer to one or more L5 buffers and the number of L5 buffers driven by a single L4 buffer. For each incremental value of the network feature or features, one or more buffer types is specified. These buffer types have been previously modeled in the environment of the incremental value of the network features and found to meet certain criteria necessary to minimize skew. If when designing a signal distribution network the designer (or design tool) chooses L4 buffers from the proper locations on the table, then skew should be minimized.
33 Citations
30 Claims
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1. A method of generating buffer data for use in selecting suitable buffer types for placement at given locations in a signal distribution network during the design of a microprocessor, the suitable buffer types being selected to minimize skew in the signal distribution network, the method comprising the following steps:
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providing a collection of buffer types available for placement at given locations within a first stage of the signal distribution network; providing a skew budget for signal propagation between the first stage and a next adjacent stage of said signal distribution network; for said first stage of the signal distribution network, providing a range of incrementally varying values of at least one feature affecting skew, at least one of said incrementally varying values depending on at least one of said given locations within said first stage; and automatically selecting, for each of said incrementally varying values, one or more suitable buffer types from among the collection of buffer types, which suitable buffer types are selected to meet the skew budget. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for generating buffer data for use in selecting suitable buffer types for placement at given locations in a signal distribution network during the design of a microprocessor, the suitable buffer types being selected to minimize skew in the signal distribution network, the system comprising:
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an input interface for accepting as input parameters (i) a collection of buffer types available for placement at given locations within a first stage of the signal distribution network, (ii) a skew budget for signal propagation between the first stage and a next adjacent stage of said signal distribution network;
(iii) a range of incrementally varying values of at least one feature affecting skew, at least one of said incrementally varying values depending on at least one of said given locations within said first stage; anda computational module for automatically selecting, for each of said incrementally varying values, one or more suitable buffer types from among the collection of buffer types, which suitable buffer types are selected to meet the skew budget. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A machine readable medium storing program instructions for generating buffer data for use in selecting suitable buffer types for placement at given locations in a signal distribution network during the design of a microprocessor, the suitable buffer types being selected to minimize skew in the signal distribution network, the machine readable medium comprising instructions for performing the following steps:
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providing a collection of buffer types available for placement at given locations within a first stage of the signal distribution network; providing a skew budget for signal propagation between the first stage and a next adjacent stage of said signal distribution network; for said first stage of the signal distribution network, providing a range of incrementally varying values of at least one feature affecting skew, at least one of said incrementally varying values depending on at least one of said given locations within said first stage; and automatically selecting, for each of said incrementally varying values, one or more suitable buffer types from among the collection of buffer types, which suitable buffer types are selected to meet the skew budget. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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Specification