Synthesis of clock tree topologies to implement nonzero clock skew schedule

Designing the topology of a clock distribution network is considered for a synchronous digital integrated circuit so as to satisfy a nonzero clock skew schedule. A methodology and related algorithms for synthesising the topology of the clock distribution network from a clock schedule derived from circuit timing information are presented. A new formulation of the problem of designing the clock distribution network is given as an efficiently solvable integer linear programming problem. The approach is demonstrated on the suite of ISCAS´89 benchmark circuits. Up to 64% performance improvement is attained on these circuits by exploiting nonzero clock skew throughout the synchronous system. Clock tree topologies that implement the nonzero clock skew schedule based on the synthesis algorithms presented are described for each of the benchmark circuits