Abstract: A method for routing clock signals in an integrated circuit provides a hierarchical routing scheme in which the lowest level clock buffers are first placed row by row in preallocated locations and routed to the input pins of standard cells receiving the output clock signals of these clock buffers. Under the method, the number of clock buffers to be placed in each row is computed according to estimates of their load capacitances and expected wiring lengths within a window. The output buffers of the same clock signal are gridded or strapped together to minimize clock skew. A second level of clock buffers are then assigned to drive the lowest level buffers. The hierarchy can be extended to any number of higher levels, until clock signals are routed for the entire integrated circuit. The higher level clock signals can also be strapped or gridded to minimize clock skew.

Abstract: A method for routing clock signals in an integrated circuit provides a hierarchical routing scheme in which the lowest level clock buffers are first placed row by row in preallocated locations and routed to the input pins of standard cells receiving the output clock signals of these clock buffers. Under the method, the number of clock buffers to be placed in each row is computed according to estimates of their load capacitances and expected wiring lengths within a window. The output buffers of the same clock signal are gridded or strapped together to minimize clock skew. A second level of clock buffers are then assigned to drive the lowest level buffers. The hierarchy can be extended to any number of higher levels, until clock signals are routed for the entire integrated circuit. The higher level clock signals can also be strapped or gridded to minimize clock skew.