72 results about "Clock tree synthesis" patented technology

A method is disclosed for synthesizing a clock tree for a partitioned integrated circuit (IC) layout comprising a plurality of base level partitions and a top level partition each occupying a separate area of a semiconductor substrate. The base level partitions include syncs to be clocked by edges of a clock signal applied to an entry node within the area occupied by the top level partition. In accordance with the method, a plurality of independently balanced subtrees are separately synthesized. Each subtree resides within the area occupied by a separate base level partition and includes a start point at a perimeter of the area occupied by that base level partition and a network of buffers and signal paths for conveying a clock signal edge from the start point to each sync included within that area. Thereafter a top level portion of the clock tree is synthesized. The top level portion of the subtree resides within the substrate area containing the top level partition and conveys the clock signal from the entry point to the start point of each synthesized subtree.

A method of cell placement and clock tree synthesis includes steps of: (a) identifying critical paths in an integrated circuit design; (b) partitioning the integrated circuit design into a timing group for each of the critical paths; (c) assigning each flip-flop in a critical path to a timing group corresponding to the critical path; (d) performing a cell placement to minimize a function of propagation delay and maximum distance between flip-flops within each timing group; and (e) constructing a clock sub-net for each timing group.

A method and apparatus for rapidly selecting types of buffers which are inserted in the clock tree for high-speed VLSI design is disclosed. The developed tool can be embedded in the existing clock tree synthesis design flow to ensure minimizing the clock delay and satisfying the clock skew constrains. Given the clock tree netlist, the inserted buffers location information, the wire electrical parameters and a buffers timing library, the components delay (buffer delay and wire delay) of the clock tree can be calculated first. Then, for each I / O pin, the path delay, the clock delay and the clock skew can be obtained. Finally, using the method, a modified clock tree netlist satisfying the timing specifications can be constructed.

A method for low power clock tree synthesis using buffer insertion, removal and resizing for high-speed VLSI design is proposed. A developed tool can be embedded in the existing clock tree synthesis design flow to ensure satisfying both specifying database constrains and clock skew constrains. For a given clock tree netlist, location information of buffers, parameters of wires and buffers' timing and power library are all included. Buffer delay and wire delay of the given clock tree netlist are calculated first. Then, a feasible solution is solved if an input netlist is not feasible for given constrains. Finally, a modified low power clock tree netlist, which satisfies timing specifications, is obtained using the proposed method.

A method of designing the layout for an IC is provided, which eliminates the signal line re-routing process and which optimizes the relative skew of the clock signal. This method comprises the steps of: (a) determining prohibited areas in each of stacked wiring layers; the prohibited areas causing an obstacle to determine layout of signal lines in each of the wiring layers if clock lines are defined to intersect the prohibited areas; (b) defining layout of clock lines in each of wiring layers through a Clock Tree Synthesis process in such a way that none of the clock lines intersects the prohibited areas; and (c) defining layout of signal lines in each of the wiring layers after the step (b). Preferably, prohibited area information about a primitive cell including at least one of the prohibited areas is provided, where the prohibited area information is used in the CTS process in the step (b).

Systems and methods for application specific integrated circuit design using Chronos links are disclosed. A Chronos Link is an ASIC on-chip and off-chip interconnect communication protocol that allows interfaces to transmit and receive information. The protocol may utilize messages or signals to indicate the availability and / or readiness of information to be exchanged between a producer and a consumer allowing the communication to be placed on hold and to be resumed seamlessly. A method includes inserting gaskets and channel repeaters connected to interfaces of multiple intellectual property (IP) blocks in order to replace traditional links with Chronos Links; performing simplified floorplanning; performing simplified placement; performing simplified clock tree synthesis (CTS) and routing; and performing simplified timing closure.

In a particular embodiment, a method of generating an advanced gating cell clock tree includes determining a timing margin for a path between a clock gating cell and a digital data storage element such as a latch or flip flop. The circuit contains a clock source and when the timing margin for the path meets a predetermined threshold, the clock gating cell is automatically moved closer to the clock source. In a particular embodiment, the timing margin is automatically determined. A clock tree synthesis is performed to insert one or more buffers into the path and create an advanced gating cell clock tree.

To provide a semiconductor integrated circuit in which a clock signal supplied to each flip-flop will not be adversely affected when a functional change is made using a spare flip-flop. The semiconductor integrated circuit includes a plurality of main flip-flops which contribute to a predetermined function, a plurality of spare flip-flops, and a clock tree synthesis circuit that generates a clock signal which is adjusted for synchronizing the plurality of main flip-flops and the plurality of spare flip-flops and supplies the adjusted clock signal to the plurality of main flip-flops and the plurality of spare flip-flops.

A clock tree synthesis (CTS) apparatus, generator, and method for synthesizing a clock tree includes a plurality of clock signal generators that output different clock signals generated from a reference clock signal. The clock signal generators includes an additional logic circuit that is not recognized as an end point of the reference clock signal when the clock tree is synthesized. In one example, the clock signal generator is a flip-flop and the additional logic circuit is a tri-state buffer.

To provide a semiconductor integrated circuit device that reduces charging and discharging currents flowing through clock tree synthesis, thereby reducing current consumption of entire circuits of the semiconductor integrated circuit device.In a semiconductor integrated circuit device including a clock synchronous type circuit that operates in synchronization with either of rising and falling edges flank of a reference clock and a plurality of clock buffer circuits for distributing the reference clock to the clock synchronous type circuit, each clock buffer circuit is constituted from a first transistor that drives a load at one of the edges flank of the reference clock with which the clock synchronous type circuit does not operate in synchronization and a second transistor that drives the load at the other edge flank of the reference clock. A gate width of the first transistor is set so that a change in the edge flank is slowed down, provided that a pulse waveform of the reference clock is not destroyed. A carrier type of the second transistor is different from the carrier type of the first transistor, and the second transistor is formed to have the gate width larger than the first transistor.