International Business Machines Corporation

Motorola Corporation

Other

Sun Microsystems, Inc.

Peter Redmond O'Brien

Anirudh Devgan

David Theodore Blaauw

Matthew E Becker

Joseph W Norton

Satyamurthy Pullela

Abhijit Dharchoudhury

Eileen H You

Micah C Knapp

Tim J Edwards

Chung Lau Chan

Thomas E Dillinger

Richard Paul Wiley

Daniel J Flees

In accordance with the present invention, a method, system, computer system, and computer program product for considering clock skew in designing digital systems with latch-controlled circuits are provided. The disclosure teaches a method for determining whether logic operations can be performed within the available time and allows detailed modeling of clock skew for different domains of the integrated circuit. Taking clock skew into account for each domain, worst-case timing paths can be determined for circuits controlled by either flip-flops or latches. A design of an integrated circuit can be revised or verified using the method taught. The disclosure envisions that integrated circuits, printed circuit boards, computer systems and other components will be manufactured based upon designs developed with the method taught.

Timing analysis of latch-controlled digital circuits with detailed clock skew analysis

A process for efficiently computing moments in an interconnected circuit begins by partitioning the circuit into sets of line-like two-port circuits. Next, capacitors are converted to equivalent current sources and inductors are converted to equivalent voltage sources. From a first port, any connected voltage source which is present in line is added to the port voltage source. Then, that voltage source combined with the connected resistor and the Thevenin equivalent circuit is converted to a Norton equivalent circuit. The current source created from the conversion is added to a current source in the circuit and the Norton equivalent circuit is converted back to a Thevenin equivalent circuit. The process is recursively performed until the opposite port is reached. The moment is then computed from the final Thevenin equivalent circuit by using the voltage and current at the port. The Thevenin-Norton-Thevenin recursive process is then repeated for the opposite port.

Method and apparatus for efficient computation of moments in interconnect circuits

Realizable interconnect reduction techniques for on-chip RC interconnects are disclosed by first partitioning the original circuit into sets of two-port circuits to maintain the spatial sparsity of the reduced model. Each original two-port circuit is matched to a reduced RC circuit having a specific configuration. The moments of the original two-port circuits are calculated. Closed form expression values of the reduced circuit elements are then calculated from the moments of the original circuits. The closed form expressions for calculating the values of the elements in the reduced circuit use a reduced number of independent variables associated with the elements, thus simplifying the calculations. An efficient linear time moment computation technique is used for computing the moments for the two-port circuits.

Method and apparatus for realizable interconnect reduction for on-chip RC circuits

An adjustable and versatile shelving system for storing articles in the cargo box of a pickup truck in an efficient manner. Brackets which support load bearing members are adjustably mounted to side rails which are connected to the sidewalls of the cargo box. The connection between the brackets and the side rails enable the height of the shelf above the floor of the cargo box to be adjustable within a range of heights. An additional shelf located a spaced distance above the first shelf can be supported by inverting some of the brackets which are connected to the side rails. The brackets can also be connected to the side rails in a manner which provides a surface for securing vertically-oriented side planks above the cargo box sidewalls to temporarily extend the cargo box sidewalls. A knock down tool chest can be provided on the shelf to store tools in a secure manner, or it can be collapsed to provide extra open shelf storage space.

Shelving and storage system for a cargo box of a pickup truck

A data processing system which calculates timing delays in a circuit having a switching device (3). A computer processor (22) receives input describing a circuit and calculates the timing delays for each switching device (3) or stage. To perform each calculation the computer processor (22) models the circuit incorporating effective resistance R.sub.eff (24), Miller capacitance C.sub..mu. (7), and an associated Miller coefficient. The Miller coefficient is a defined by the behaviour of the model. The model is then reduced to a set of equations, the variables are determined, and the timing delay calculated. In one embodiment, successive stages are calculated to locate timing violations in circuit design. In alternate embodiments, models such as CRYSTAL (4) or the Sakurai model are enhanced by Miller capacitance considerations, however many other models may be used.

Method and apparatus for incorporating a miller compensation for

A process and implementing computer system (13) for optimally sizing elements of an integrated circuit includes determining actual arrival times and required arrival times (403) for processed signals at all nodes within the integrated circuit and determining the slack or difference (405) between arrival and required times for each node. If the actual arrival time for a particular node is after the time required to meet a predetermined design constraint of the node (407), a determination (411) is made regarding the effect of that element on the nodal slack for an incremental increase in the size of that element. Thereafter an element is selected (413) for sizing increase (415) in accordance with a weighting function and the process is repeated until all of the nodes in the integrated circuit have positive slack times (407, 409). One method of accomplishing a timing analysis step (303) includes an analytical circuit simulation technique (1000-1015) in which circuit 'I-V' characteristics are more precisely represented with a power series (1006) including a plurality of regional segmental approximations (901-907). Another method of timing analysis includes an equivalency methodology (1501-1513) of translating passive transistors to equivalent RC networks (801). In the overall optimization process, a method is provided (1701-1715) for automatically correcting transistor predicted sensitivities based upon a correction factor (1713). A multi-model timing method (1601-1619) is also illustrated (1601-1619) for synergistically combining fast and accurate circuit timing models to optimize the speed and accuracy of the design process itself while remaining within an accuracy threshold.

Simulation corrected sensitivity

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Austin, TX, United States of America

Peter Redmond O'Brien