Lsi Logic Corporation

Christian Joly

Zarir B Sarkari

Simon Dolan

Allen Wu

Francois Ducaroir

Sanjay Adkar

Ravichandran Ramachandran

Sarika Agrawal

Dan Kochpatcharin

A practical approach for synthesis for million gate ASICs is based on the use of synthesis shells. The synthesis shell is generated by beginning with a gate level description of a fully characterized and optimized block. This gate level description is reduced by removing internal gates to produce a synthesis shell of the synthesized block. The synthesis shell preserves input load and fanout for the block, output delay relative to clock for the block, setup/hold constraints on input signals relative to the clock for the block, and delay from input to output for pass through signals for the block. Such a synthesis shell can be used as a substitute for original design netlists and can be used for hierarchical synthesis in a customer's design environment, or as a deliverable from a provider of ASIC services in order to protect the intellectual property of such a provider. Since all the information that is needed by a synthesizer is available in the synthesis shell in netlist form, the shell is extremely accurate. The synthesis shell as mentioned above comprises a gate level description which is a subset of the synthesized block. This description is reduced by deleting elements of the gate level description according to a set of pre-specified criteria.

Synthesis shell generation and use in ASIC design

An ASIC design methodology in which portions of the ASIC are implemented in silicon or other suitable semiconductor technology at an early stage in the design flow through the use of a series of interim devices. The invention provides a method in which additional portions or subsystems of the integrated circuit are incorporated into successive versions of the interim device. In this manner, the invention provides for the gradual incorporation of a plurality of architectural subsystems into the integrated device such that the synthesis and verification of each iteration is broken into manageable pieces. In the preferred embodiment, this design method is facilitated by incorporating a programmable portion into the design flow of each interim device such that each interim device includes a custom portion into which the subsystems that have been implemented in silicon are fabricated and a programmable portion. The programmable portion is useful in permitting the designer to make modifications to the subsystems implemented in the custom portion or to simulate the subsystems of the target device that have yet to be implemented in the custom portion.

Method for designing application specific integrated circuits

An integrated circuit comprised of a customized circuit portion and a programmable logic portion that is interfaced to the customized circuit. The custom circuit and the programmable circuit are fabricated on a common semiconductor substrate to achieve maximum cost savings and performance advantages over implementations in which an external PLD or other programmable device is interfaced to a custom circuit. Suitably, the customized circuit is designed with an ASIC design flow to optimize the performance, power consumption, and size of the customized circuit. In the presently preferred embodiment, the programmable circuit comprises a plurality of programmable logic cells suitably generated by, in one embodiment, a PLD compiler. Ideally, the relative size and placement of said PLD with respect to said customized circuit are selectable during a design phase of said integrated circuit. This provides flexibility in determining how much of an interim device need be devoted to programmable circuitry. Presumably, during earlier stages of the design process, a larger percentage of the device will be devoted to the programmable portion. As the product definition matures, subsequent interim devices contemplated herein require less programmable logic.

PLD/ASIC hybrid integrated circuit

A method for creating a shell to represent a functional block of an IC design comprising of a plurality of interconnected functional blocks. The critical information from a synthesized gate level block is retained in the shell such that when analyzing the static characteristics of another block connected to the block now represented by the shell the analysis is still accurate. At a hierarchial level the present invention provides a method for analyzing the functional blocks of an IC design such that the memory requirement for storing the information of the functional blocks of the IC design is reduced as well as a decrease in run time.

Method for creating and using design shells for integrated circuit

Gate level netlists used for timing analysis in integrated circuit design are reduced using a timing shell generator while preserving critical information for timing analysis. After verification of timings, the gate level netlist is convened into a shell containing block boundary information. The function of the shell generator is to delete internal cells meeting a set of criteria. The result is a shell netlist containing a subset of the original netlist. Thus, the design cycle time involved and computing time and resources needed in ASIC development for chips using circuits represented by timing shell netlists are decreased by substituting design verification at the top level of large hierarchical netlists or large flat netlists by bottom up verification procedures using timing shells.

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Palo Alto, CA, United States of America

Christian Joly