Decoupling capacitor planning with analytical delay model on RLC power grid

Abstract

Abstract-Decoupling capacitors (decaps) are typically used to reduce the noise in the power supply network. Because the delay of gates and interconnects is affected by the supply voltage level, decaps can be used to improve the circuit performance as well. In this paper, we present the analytical delay model under IR drop, Ldi/dt noise, and decaps to study how decaps affect both the gate and interconnect delay. Given a floorplanning solution, we study how to allocate the whitespace for decap insertion so that the delay is minimized under the given noise and area constraint. We employ the Sequential Linear Programming method to solve the non-linear whitespace allocation problem. Our experimental results show that intelligent decap allocating decap makes further delay reduction possible without adding any additional decap.