CONTANGO: Integrated Optimization of SoC Clock Networks

On-chip clock networks are remarkable in their impact on the performance and power of synchronous circuits, in their susceptibility to adverse effects of semiconductor technology scaling, as well as in their strong potential for improvement through better CAD algorithms and tools. Existing literature is rich in ideas and techniques but performs large-scale optimization using analytical models that lost accuracy at recent technology nodes and have rarely been validated by realistic SPICE simulations on large industry designs. Our work offers a methodology for SPICE-accurate optimization of clock networks, coordinated to satisfy slew constraints and achieve best tradeoffs between skew, insertion delay, power, as well as tolerance to variations. Our implementation, called Contango, is evaluated on 45 nm benchmarks from IBM Research and Texas Instruments with up to 50 K sinks. It outperforms all published results in terms of skew and shows superior scalability.