Patents by Inventor Sharad Mehrotra

Sharad Mehrotra has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6735754
    Abstract: A system that facilitates generating a global routing for a layout of an integrated circuit operates by receiving a netlist to be routed. The system partitions this netlist into global signals, datapath signals, and control signals. Next, the system creates a tiling grid of the integrated circuit and routes connection nets between tiles within this grid. The system then selects an area within the integrated circuit larger than a tile in the first grid. The system creates a second grid of tiles smaller than the tiles of the first grid within this selected area. During this process, connection nets are routed between tiles on the second grid while routings within the first grid are maintained. The system merges connection nets within the first grid with connection nets within the second grid to form the global routing.
    Type: Grant
    Filed: June 6, 2002
    Date of Patent: May 11, 2004
    Assignee: Sun Microsystems, Inc.
    Inventors: Sharad Mehrotra, Parsotam T. Patel
  • Patent number: 6694502
    Abstract: Provided is a data structure containing wiring information for an integrated circuit and a method for storing the same in a computer readable medium. In one embodiment of the present invention storage of the data structure is achieved by mapping said integrated circuit into memory locations of said medium as a wiring plane having a plurality of data points arranged in a grid. Each of the plurality of data points having state information associated therewith, which includes a plurality of attributes. Subsections of the grid are associated with memory locations in the computer readable medium to form a plurality of tiles. Specifically the tiles and data points are arranged so that a sub-portion of the data points associated with one of the plurality of tiles have common attributes.
    Type: Grant
    Filed: November 2, 2001
    Date of Patent: February 17, 2004
    Assignee: Sun Microsystems, Inc.
    Inventors: Sharad Mehrotra, Parsotam T. Patel
  • Publication number: 20030229876
    Abstract: A system that facilitates generating a global routing for a layout of an integrated circuit operates by receiving a netlist to be routed. The system partitions this netlist into global signals, datapath signals, and control signals. Next, the system creates a tiling grid of the integrated circuit and routes connection nets between tiles within this grid. The system then selects an area within the integrated circuit larger than a tile in the first grid. The system creates a second grid of tiles smaller than the tiles of the first grid within this selected area. During this process, connection nets are routed between tiles on the second grid while routings within the first grid are maintained. The system merges connection nets within the first grid with connection nets within the second grid to form the global routing.
    Type: Application
    Filed: June 6, 2002
    Publication date: December 11, 2003
    Inventors: Sharad Mehrotra, Parsotam T. Patel
  • Patent number: 6615395
    Abstract: A method for performing a static timing analysis on an integrated circuit chip or module taking into account the effect of wiring interconnection coupling is described. The wiring interactions are modeled as appropriate equivalent grounded capacitances, allowing traditional delay calculation methods to be applied.
    Type: Grant
    Filed: December 20, 1999
    Date of Patent: September 2, 2003
    Assignee: International Business Machines Corporation
    Inventors: David J. Hathaway, Chandramouli V. Kashyap, Byron L. Krauter, Sharad Mehrotra, Alexander J. Suess
  • Patent number: 6601222
    Abstract: Disclosed is a method for pre-design estimation of coupling noise and avoidance of coupling noise failures in interconnects. An initial routing of a plurality of nets is estimated utilizing global paths. Then, the worst-case and average-case models for various parameters of each net are evaluated. With these models, a noise analysis is completed by which a determination is made whether coupling noise of any one of the nets is above a threshold level for noise-induced failure (i.e., a noise-failure threshold). When it is determined that the estimated coupling noise of a net falls below the noise-failure threshold, a response mechanism is triggered for later implementation during detailed routing of the nets to prevent the coupling noise from reaching the noise-failure threshold.
    Type: Grant
    Filed: October 13, 2000
    Date of Patent: July 29, 2003
    Assignee: International Business Machines Corporation
    Inventors: Sharad Mehrotra, Parsotam Trikam Patel, David J. Widiger
  • Publication number: 20030088843
    Abstract: Provided is a data structure containing wiring information for an integrated circuit and a method for storing the same in a computer readable medium. In one embodiment of the present invention storage of the data structure is achieved by mapping said integrated circuit into memory locations of said medium as a wiring plane having a plurality of data points arranged in a grid. Each of the plurality of data points having state information associated therewith, which includes a plurality of attributes. Subsections of the grid are associated with memory locations in the computer readable medium to form a plurality of tiles. Specifically the tiles and data points are arranged so that a sub-portion of the data points associated with one of the plurality of tiles have common attributes.
    Type: Application
    Filed: November 2, 2001
    Publication date: May 8, 2003
    Applicant: SUN MICROSYSTEMS, INC.
    Inventors: Sharad Mehrotra, Parsotam T. Patel
  • Patent number: 6532574
    Abstract: Adjacent signal lines within the critical path of logic within an integrated circuit are checked for capacitive coupling induced signal delay variations resulting from concurrent signal transitions. When found, signal transition overlap is eliminated by delaying the clock edge (rising or falling) triggering the signal driving logic, without necessarily delaying the other clock edge. A delay circuit is incorporated into clock stages for the signal driving logic, and may be selectively actuated to delay the clock edge to particular signal driving logic circuits. Selection of signal lines in which signal transitions are to be delayed may be performed after manufacture of the integrated circuit, and iterative determinations may be required since signal adjustment may create new critical paths within the integrated circuit logic.
    Type: Grant
    Filed: August 17, 2000
    Date of Patent: March 11, 2003
    Assignee: International Business Machines Corporation
    Inventors: Christopher McCall Durham, Sharad Mehrotra, Alexander Koos Spencer, Barry Duane Williamson
  • Patent number: 6523149
    Abstract: A method, system and apparatus is provided to perform noise analysis of electrical circuits. The method and system partitions an original multi-port circuit to a reduced circuit model having a specific layout configuration. The reduced circuit model may have a variety of configurations. Then an input signal is applied to a first port of the reduced circuit model using the specific layout configuration and an output signal is measured from a second port of the reduced circuit model. The process continues until all input ports which may contribute noise to the circuit are measured and then the results are calculated to determine the total output of simulated noise experienced by the circuit. The calculated output results of the reduced circuit model are then used to determine whether the original circuit is designed to withstand the quantity of noise experienced by the reduced circuit model.
    Type: Grant
    Filed: September 21, 2000
    Date of Patent: February 18, 2003
    Assignee: International Business Machines Corporation
    Inventors: Sharad Mehrotra, Mark W. Wenning, David J. Widiger
  • Patent number: 6510540
    Abstract: This invention reduces pessimism in cross talk analysis of digital circuits by combining only the peak noises from aggressor nets that can switch simultaneously during the time interval when the downstream receiving latch can sample the errant data. This is done by, first, determining aggressor switching windows and victim sensitivity windows. These windows are then used to determine which combination of noise sources can temporally align so as to cause the greatest noise within the victim sensitivity window.
    Type: Grant
    Filed: August 17, 2000
    Date of Patent: January 21, 2003
    Assignee: International Business Machines Corporation
    Inventors: Byron Lee Krauter, Sharad Mehrotra, Jonathan Humphrey Saxman, Paul Gerard Villarrubia, David J. Widiger
  • Patent number: 6467069
    Abstract: A method for timing and noise analysis in designing data processing chips is provided. The process begins by wiring all unconnected nets in the design and then using a 2½ D capacitance extraction technique built into a detailed router to extract all of the wired nets. The data from the extracted nets is then process using a timing and analysis tool. Optimization programs are then used to generate fixes for any nets in the design which contribute to timing and noise failures. The present invention gives designers the capability of fast and accurate interconnect extraction within the routing tool. In addition, this technique is incremental. Any wiring changes can be quickly re-extracted, since only local information is required for extraction. This incremental capability allows designers to perform quick iterations of wiring, extraction and timing analysis.
    Type: Grant
    Filed: December 15, 2000
    Date of Patent: October 15, 2002
    Assignee: International Business Machines Corporation
    Inventors: Sharad Mehrotra, Parsotam Trikam Patel
  • Patent number: 6430654
    Abstract: A multi-level cache and method for operation therefore includes a first non-blocking cache receiving access requests from a device in a processor, and a first miss queue storing entries corresponding to access requests not serviced by the first non-blocking cache. A second non-blocking cache is provided for receiving access requests from the first miss queue, and a second miss queue is provided for storing entries corresponding to access requests not serviced by the second non-blocking cache. Other queueing structures such as a victim queue and a write queue are provided depending on the particular structure of the cache level within the multilevel cache hierarchy.
    Type: Grant
    Filed: January 21, 1998
    Date of Patent: August 6, 2002
    Assignee: Sun Microsystems, Inc.
    Inventors: Sharad Mehrotra, Ricky C. Hetherington
  • Patent number: 6415422
    Abstract: A method for performing capacitance estimations on an integrated circuit design routed by a global routing tool is disclosed. Routing areas and pin locations of a net within an integrated circuit design are initially obtained from a global routing tool. Common boundaries among the routing areas are then defined. Before the performance of a detailed routing step, congestion information furnished by the global routing tool is utilized to perform probabilistic capacitance calculations for an interconnect that can be routed within the routing areas via the defined common boundaries to connect the pin locations.
    Type: Grant
    Filed: September 17, 1999
    Date of Patent: July 2, 2002
    Assignee: International Business Machines Corporation
    Inventors: Sharad Mehrotra, Parsotam Trikam Patel
  • Publication number: 20020078425
    Abstract: A method for timing and noise analysis in designing data processing chips is provided. The process begins by wiring all unconnected nets in the design and then using a 2-½ D capacitance extraction technique built into a detailed router to extract all of the wired nets. The data from the extracted nets is then processed using a timing and analysis tool. Optimization programs are then used to generate fixes for any nets in the design which contribute to timing and noise failures. The present invention gives designers the capability of fast and accurate interconnect extraction within the routing tool. In addition, this technique is incremental. Any wiring changes can be quickly re-extracted, since only local information is required for extraction. This incremental capability allows designers to perform quick iterations of wiring, extraction and timing analysis.
    Type: Application
    Filed: December 15, 2000
    Publication date: June 20, 2002
    Applicant: IBM Corporation
    Inventors: Sharad Mehrotra, Parsotam Trikam Patel
  • Patent number: 6226713
    Abstract: A multi-level cache and method for operation thereof is presented for processing multiple cache system accesses simultaneously and handling the interactions between the queues of the cache levels. The cache unit includes a non-blocking cache receiving data access requests from a functional unit in a processor, and a miss queue storing entries corresponding to data access requests not serviced by the non-blocking cache. A victim queue stores entries of the non-blocking cache which have been evicted from the non-blocking cache, while a write queue buffers write requests into the non-blocking cache. Controller logic is provided for controlling interaction between the miss queue and the victim queue. Controller logic is also provided for controlling interaction between the miss queue and the write queue. Controller logic is also provided for controlling interaction between the victim queue and the miss queue for processing cache misses.
    Type: Grant
    Filed: January 21, 1998
    Date of Patent: May 1, 2001
    Assignee: Sun Microsystems, Inc.
    Inventor: Sharad Mehrotra
  • Patent number: 6154812
    Abstract: A data cache unit associated with a processor, the data cache unit including a first non-blocking cache receiving a data access from a device in the processor. A second non-blocking cache is coupled to the first non-blocking cache to service misses in the first non-blocking cache. A data return path coupled to the second non-blocking cache couples data returning from the second non-blocking cache to both the first non-blocking cache and the device generating the access to the first non-blocking cache.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: November 28, 2000
    Assignee: Sun Microsystems, Inc.
    Inventors: Ricky C. Hetherington, Sharad Mehrotra, Ramesh Panwar
  • Patent number: 6148372
    Abstract: A multi-level cache and method for operation thereof is presented for processing multiple cache system accesses simultaneously. The cache includes a first non-blocking cache receiving data access requests from a device in a processor, and a first miss queue storing entries corresponding to data access requests not serviced by the first non-blocking cache. A second non-blocking cache is provided and receives data access requests from the first miss queue, and a second miss queue stores entries corresponding to data access requests not serviced by the second non-blocking cache. A first arbiter arbitrates between two or more access requests to the first non-blocking cache. A second arbiter can be provided to arbitrate between two or more access requests to the second non-blocking cache.The arbiter is capable of determining if an anticipatory stall signal should be asserted if any of the cache resources, such as a queuing structure, is becoming overloaded.
    Type: Grant
    Filed: January 21, 1998
    Date of Patent: November 14, 2000
    Assignee: Sun Microsystems, Inc.
    Inventors: Sharad Mehrotra, Michelle L. Wong
  • Patent number: 6148371
    Abstract: A data cache unit associated with a processor, the data cache unit including a first non-blocking cache receiving a data access from a device in the processor. A second non-blocking cache is coupled to the first non-blocking cache to service misses in the first non-blocking cache. A data return path coupled to the second non-blocking cache couples data returning from the second non-blocking cache to both the first non-blocking cache and the device generating the access to the first non-blocking cache.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: November 14, 2000
    Assignee: Sun Microsystems, Inc.
    Inventors: Ricky C. Hetherington, Sharad Mehrotra, Ramesh Panwar
  • Patent number: 6145054
    Abstract: A method and apparatus for merging multiple misses to a multi-level cache is provided to improve the performance of the cache. A first and second non-blocking cache are each provided with miss queues storing entries corresponding to access requests not serviced by the respective caches. The first and second miss queues have an indicator associable with each of said entries in the respective miss queues indicating that the entry is a primary reference to data located at the address associated with said entry. If a subsequent instruction generates a cache miss accessing data associated with an entry in a miss queue, the subsequent miss is merged with the appropriate entry in the miss queue and serviced when the primary reference is serviced.
    Type: Grant
    Filed: January 21, 1998
    Date of Patent: November 7, 2000
    Assignee: Sun Microsystems, Inc.
    Inventors: Sharad Mehrotra, Ricky C. Hetherington, Michelle L. Wong
  • Patent number: 6086238
    Abstract: A method and system for shape processing within an integrated circuit layout for parasitic capacitance estimation is disclosed. In accordance with the method and system of the present invention, a set of coordinates of an overlapping region formed by at least one interconnect is first identified. Subsequently, each metal layer present within the overlapping region is classified. Each interconnect edge present on each side of the overlapping region is then determined. Finally, a neighbor in a direction perpendicular to each side of the overlapping region is determined. By so doing, the parasitic capacitance between the overlapping region and its determined neighbors can be evaluated.
    Type: Grant
    Filed: October 7, 1996
    Date of Patent: July 11, 2000
    Assignee: International Business Machines Corporation
    Inventors: Sharad Mehrotra, Paul Gerard Villarrubia, David James Widiger
  • Patent number: 6081873
    Abstract: A data cache unit associated with a processor, the data cache unit including a multi-ported non-blocking cache receiving a data access request from a lower level device in the processor. A memory scheduling window includes at least one row of entries, wherein each entry includes an address field holding an address of the access request. A conflict map field within at least some of the entries is coupled to a conflict checking unit. The conflict checking unit responds to the address fields by setting bits in the conflict map fields to indicate intra-row conflicts between entries. A picker coupled to the memory scheduling window responds to the conflict map fields so as to identify groups of non-conflicting entries to launch in parallel at the multi-ported non-blocking cache.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: June 27, 2000
    Assignee: Sun Microsystems, Inc.
    Inventors: Ricky C. Hetherington, Sharad Mehrotra, Ramesh Panwar