Unisys Corporation

Micron Technology Incorporated

Joseph P Kerzman

James Edward Rezek

Mark D Aubel

Merwin H Alferness

Kevin R Duncan

Douglas A Fuller

Steven G Wurzer

Neil Petrie

David R Johnson

Charles R Caldarale

James R McBreen

John T Rusterholz

Robert E Garnett

John Steven Kuslak

David C Johnson

Hans Christian Mikkelsen

Wayne D Ward

Kenneth L Engelbrecht

Robert J Palermo

Richard F Paul

John Z Nguyen

Richard M Shelton

Eric S Collins

Duane G Kurth

James W Douglas

Donna J Plunkett

Francis A Stephens

James M Nead

Mark A Vasquez

Arthur F Boehm

Apparatuses and methods for phase interpolators are provided. An example apparatus comprises a phase interpolator and a controller coupled to the phase interpolator. The controller is configured to provide a digital timing code to the phase interpolator, and the phase interpolator is configured to apply a correction to the received digital timing code based, at least in part, on phase interpolator error correction data from a data structure containing phase interpolator error correction data.

Phase interpolator

A method and apparatus for efficiently viewing selected cells using a database editor tool. By using a cell selection list that identifies a number of selected components, the present invention may allow the user to sequentially view the selected components by using a number of pre-defined 'hot-keys'. In addition, the present invention may automatically set the design hierarchy in the database editor tool to an appropriate level so that the component being viewed can be easily manipulated by the circuit designer.

Method and apparatus for efficiently viewing a number of selected components using a database editor tool

A method and apparatus for associating selected circuit instances, and for allowing a later group manipulation thereof. Prior to entering a database editor tool, selected instances may be associated with one another, and the association may be recorded in the circuit design database. The database editor tool may then read the circuit design database and identify the selected instances and the association therebetween. The associated instances may be called a group, or preferably a stack. The database editor tool may then perform a group operation on the instances associated with the stack.

Method and apparatus for associating selected circuit instances and for performing a group operation thereon

Methods and apparatus for efficiently identifying, selecting and aligning cells within a circuit design are disclosed. Preferably, a net or group-of nets is first identified by the circuit designer. Then, selected cells that are connected to the selected net or group of nets are identified by the placement tool. A qualification or filter may be provided for filtering which cells are selected. For example, the filter may allow only those cells that are source cells, destination cells, placed cells, unplaced cells, etc., or any combination thereof to be selected. The selected cells may be aligned in a direction of an alignment axis, if desired.

Method and apparatus for selecting and aligning cells using a placement tool

A placement tool that may import and export cell substitution and/or cell selection lists. The cell substitution and/or cell selection lists may be used by the placement tool to substitute and/or modify the placement design database, rather than the original schematic or behavioral database. This may eliminate the need to re-synthesize the circuit design during each design iteration. The present invention further contemplates providing a reset feature which may reset the circuit design database to a previous state, if desired.

Method and apparatus for using a placement tool to manipulate cell substitution lists

A method and apparatus for efficiently selecting cells within a circuit design database. The invention includes four primary features for selecting cells including (1) selecting only those cells that are in a pre-identified region and within a pre-identified selection area; (2) maneuvering through the circuit design hierarchy and selecting cells or regions at selected levels of hierarchy by using predetermined up and down hot-keys; (3) sorting selected cells by instance name, and manually selecting a desired cell or region from the resulting sorted list; and (4) sorting selected cells by a corresponding net name, and manually selecting a desired cell or region from the resulting sorted list.

Method and apparatus for selecting components within a circuit design database

Method and apparatus for efficiently traversing and placing cells in a circuit design database are disclosed. In one illustrative embodiment, one or more leaf cells are identified as base objects. The base objects are placed and aligned along a selected dominate axis. Once the base objects are identified, an input port is identified by the circuit designer. In many cases, selected base objects will have at least one common input port name, such as &ldquo;A&rdquo;. By selecting a common input port name, the corresponding input port for each of the selected base objects is identified. Once identified, the source leaf cells that have an output port that is coupled to the identified input ports can be identified, placed and aligned as desired.

Method and apparatus for traversing and placing cells using a placement tool

A method and apparatus for selectively viewing nets within a database editor tool. The present invention provides four primary features for selectively viewing nets. First, the present invention contemplates selecting a number of objects, and viewing only those nets that are either driven from or received by the selected objects. In a preferred embodiment, the number of objects are placed objects within a placement tool. Second, for those nets that are selected, and that are also coupled to un-placed cells, the present invention contemplate providing fly-wires from the corresponding selected objects to a predetermined location representative of an approximate expected location for the un-placed cells. Third, the present invention contemplate providing a vector filter which may permit only vectored nets with a selected bus width range to be viewed. Finally, the fourth feature of the present invention contemplates providing a means for selectively viewing only those nets that cross a predetermined hierarchical boundary within the circuit design database.

Method and apparatus for selectively viewing nets within a database editor tool

A system and method for interprocess communication between concurrently executing, cooperating sequential processes in a digital computer system uses a shared memory queue as a mechanism for message passing and process synchronization. Data to be transferred from a sending process to a receiving process is stored in a queue entry which is visible in the virtual address space of the first process. The queue entry is added to a queue by the sending process directing the processor to execute an enqueue instruction. The receiving process removes the queue entry from the queue by directing the processor to execute a dequeue instruction. The receiving process then has direct access and visibility to the contents of the queue entry without having to copy the data into its virtual address space. Instead of sending data in a queue entry, a sending process may send an event indicator and no data. The receiving process may then wait on an empty queue until an event notification is received in a queue entry enqueued to the queue. Protection is provided by the system to prevent unauthorized access to the queue by other processes active in the system.

System architecture for improved message passing and process

A method and apparatus for distributing clock drivers within a hierarchical circuit design, wherein the clock drivers are concentrated in locations where they are actually needed rather than uniformly distributed throughout the circuit design. In an exemplary embodiment, the actual clock loads within a selected hierarchical region are determined, and a sufficient number of clock drivers are added as children objects to the selected hierarchical region. Since many placement tools may place the children objects within an outer boundary of the corresponding parent object, the clock drivers, as children objects of the selected hierarchical region, may be placed within the outer boundary of the selected hierarchical region. Accordingly, the clock drivers may be concentrated in the locations where actually needed.

Method and apparatus for distributing a clock tree within a hierarchical

A method and apparatus for efficiently identifying and resolving conflicts between conflicting cell substitution recommendations. Unlike the prior art, the present invention provides a resolving means within a data processing system to identify and resolve conflicting cell substitution recommendations. The resolving means may categorize the cell substitutions in accordance with a number of predetermined cell substitution types, wherein each of the cell substitution type may be assign a predetermined priority value. Thereafter, the resolving means may identify conflicting cell substitution recommendations, and resolve the conflicts in accordance with the predetermined priority scheme.

Method and apparatus for resolving conflicts between cell substitution

A method and apparatus for efficiently optimizing a circuit design by substituting identified cells within the circuit design with logically equivalent cells having different drive strengths. The present invention eliminates the need to update the design database and to place and route the circuit design during each design iteration. Rather, an improved extraction tool is provided which incorporates a cell substitution list, and updates the RC file therefrom. The updated RC file is used by the timing analysis tool to determine if the updated design will meet the design specification. After the design meets the design specification, a final place and route may be performed.

Method and apparatus for performing drive strength adjust optimization

A method and apparatus for efficiently performing timing analysis on a circuit design. The present invention essentially provides a hybrid between a path enumeration algorithm and a critical path algorithm. As such, the present invention increases the number and degree of timing violations reported by a Critical Path Analysis (CPA) algorithm, while maintaining a performance advantage over a Path Enumeration (PE) algorithm. This is accomplished by providing a number of 'pseudo' clocks to selected latches within the circuit design database, thereby tricking the CPA algorithm into reporting more timing violations than would otherwise be reported.

Growing community of inventors

New Brighton, MN, United States of America

Joseph P Kerzman