Integrated logic circuit and hierarchical design method thereof
View Patent ↗Modules 14 to 18 are disposed in a chip 10 , and the module 14 includes a plurality of external buffer cells 20 disposed along the peripheral of the module 14 , and an internal circuit 21 disposed inside the plurality of external buffer cells 20 . Input and output of signals is made between the internal circuit 21 and the external circuit, through the external buffer cells 20 . The output-stage transistor of each external buffer cell has a larger size than the transistor size of the internal circuit 21 . The external buffer cells 20 have a driving capability for enabling direct driving of a transistor inside the chip through a wire having the maximum Manhattan length of a module-disposed region in on chip. If the disposed area of the plurality of external buffer cells 20 is not sufficient, the size of the module is enlarged, or repartition is made to reform the modules so that the plurality of external buffer cells 20 have their sufficient disposed area.
1. A hierarchical design method of an integrated logic circuit wherein at least one of a plurality of modules of a top level in hierarchical design comprises an internal circuit; and a plurality of external buffer cells, disposed along a periphery of the internal circuit, through which signal input/output is made between the internal circuit and a chip I/O cell or another of the plurality of modules, the method comprising:
providing the external buffer cells each having a driving capability for enabling direct driving of a transistor inside the chip through a wire with a maximum Manhattan length in a module-disposed region on the chip: and
disposing the plurality of modules and determining position of each of the external buffer cells, based on a temporary wiring between the plurality of modules and between ones of the plurality of modules and the chip I/O cells.
2. The hierarchical design method according to claim 1 , further comprising between the providing and the disposing:
enlarging a size of the module having the plurality of external buffer cells so that the plurality of external buffer cells have their sufficient disposed area, if the disposed area is not sufficient.
3. The hierarchical design method according to claim 1 , further comprising between the providing and the disposing:
repartitioning to reform the plurality of modules so that the plurality of external buffer cells have their sufficient disposed area, if the disposed area is not sufficient.