Timing-Aware Decoupling Capacitance Allocation in Power Distribution Networks

Power supply noise increases the circuit delay, which may lead to performance failure of a design. Decoupling capacitance (decap) addition is effective in reducing the power supply noise, thus making the supply network more robust in presence of large switching currents. Traditionally, decaps have been allocated in order to minimize the worst-case voltage drop occurring in the power grid. In this paper, we propose an approach for timing-aware decap allocation which uses global time slacks to drive the decap optimization. Non-critical gates with larger timing slacks can tolerate a relatively higher supply voltage drop as compared to the gates on the critical paths. The decap allocation is formulated as a non-linear optimization problem using Lagrangian relaxation, and modified adjoint method is used to efficiently obtain the sensitivities of objective function to decap sizes. A fast path-based heuristic is also implemented and compared with the global optimization formulation. The two ...

• Type: Conference
• Year: 2007
• Where: ASPDAC
• Authors: Sanjay Pant, David Blaauw
• Keywords: ASPDAC 2007, Decap Allocation, Hardware, Power Supply Noise, Total Decap