Timing-constrained power minimization in VLSI circuits by simultaneous multilayer wire spacing

• Multi-layer interconnect power optimization under timing constraints is described.
• Related global optimization problem is formulated.
• An algorithm for solving optimization problem is described and implemented.
• A mathematical relation to similar optimization problems is developed.
• 5–12% dynamic interconnect power reduction on industrial cases is demonstrated.

Reduction of interconnect delay and interconnect power has become a primary design challenge in recent CMOS technology generations. Spacing between wires can be modified so that line-to-line capacitances will be optimized for minimal power under timing constraints. In this paper, we present a novel algorithm for simultaneous multilayer interconnect spacing that minimizes the total dynamic power dissipation caused by an interconnect, while maximum delay constraints are satisfied. A multi-dimensional visibility graph is used to represent the problem, and a layout partitioning technique is applied to solve the problem efficiently. The algorithm was evaluated on an industrial microprocessor designed using the 32 nm technology, and it achieved a 5–12% reduction in interconnect switching power.