A method of placing and routing elements of a semiconductor integrated circuit picks out a signal net, a driver of the signal net, and load cells driven by the driver among the elements of the integrated circuit, places the driver at a first position, defines a first range based on the first position, determines a second position in the first range, defines a second range based on the second position, and collectively places the load cells of a predetermined number in the second range. Namely, the method deals with a signal net in the integrated circuit, a driver of the net, and load cells driven by the driver. The method sets conditions on the signal net, driver, and load cells, when placing and routing the elements of the integrated circuit, to thereby reduce skew (skew time), wiring overhead, and time delay in the integrated circuit and speedily and easily place and route the elements.
Provided is a technique for reducing skew in routing a clock signal in an integrated circuit device by prerouting an H trunk, dividing the H trunk into parts, and balancing delays in one of the parts by adding snaking wire. In a more particular aspect, the clock signal is prerouted as an H trunk, and the H trunk is divided into a left-top quadrant, a left-bottom quadrant, a right-top quadrant, and a right-bottom quadrant. The signal delays are balanced as between the two left quadrants by adding snaking wire, the signal delays are balanced between the two right quadrants by adding snaking wire, and the signal delays are balanced between the right half and the left half by adding snaking wire.
In a layout method for an LSI having a plurality of cells, automated arrangement of cells is performed on the basis of a netlist, which has cells and connection data therefor, and timing conditions, and, once a timing optimization processing is performed so that a plurality of cells are arranged on a chip, global wiring processing is implemented and the wiring congestion rate is analyzed. In addition, in small regions where a wiring congestion rate is so high that detailed wiring processing is judged to be difficult, cell rearrangement processing is implemented. Next, detailed wiring processing is performed with respect to the cells which have been rearranged. The rearrangement of cells is performed only in small regions with a high congestion rate, with the result that the overall cell arrangement in which timing is optimized is not changed markedly, whereby it is possible to reduce the probability of wiring being impossible in the course of the detailed wiring processing.
The specification discloses a for reduction of net delays and insertion of buffers in a logic tree having a root and a plurality of leaves. The steps of the method include inserting a plurality of auxiliary nodes into the, defining discrete, approximate scales for delay, load, and ramp time, constructing a set of buffers chains for later insertion into the net tree, determining for each node on the tree a tradeoff function relating ramp time, departure time and load at the node, for each node, removing combinations of the tradeoff functions and the buffer chains, which when inserted into the tradeoff function, lead to a ramp time which exceeds a predetermined maximum allowable ramp time, for each node, using the tradeoff function to determine a minimum delay to insert, and inserting the buffer chain corresponding to the minimum delay as determined by the tradeoff function.
To implement a method of laying out interconnections, which is capable of reducing a skew value of a predetermined signal and a delay in predetermined signal to the utmost, a region intended for a wiring layout employed in a CAD system is divided into a plurality of subregions and wiring regions dedicated to the predetermined signal in the respective subregions are set. The number of driver's stages in the respective subregions is set and the region is enlarged with the adjacent subregions identical in number of driver's stages as virtual subregions. Thus, the layout of wiring between the subregions is set.
A method, system, and computer product are disclosed for improving wireability near clock nets in a logic design that includes multiple logic blocks. Each of the logic blocks has an actual physical size. Logic blocks that are a particular type are identified. During placement of the logic blocks, an apparent physical size of each of the identified logic blocks is utilized as a physical size for the identified logic block. The apparent physical size is larger than the actual physical size. During routing, the actual physical size of each of the identified logic blocks is utilized.
