A method and apparatus for selecting programmable interconnects to reduce
clock skew is described. A routing tree for clock signals is created
having routes and clock pin nodes. Delays of the clock signals to the
clock pin nodes are determined. The routing tree is balanced to a target
clock skew, such as zero clock skew, for the clock signals provided to
the clock pin nodes. Programmable interconnect circuits are selectively
added to reduce clock skews of the clock signals, where the clock skews
being reduced at the clock pin nodes are for at least a portion of the
clock pin nodes. Additionally described are determining clock propagation
delays to clock pins and balancing a clock tree using computer aided
design.