Decoupling Capacitor Optimization for Nanotechnology Designs

On-chip MOS decoupling capacitors (DECAPs) are widely used to reduce power supply noise. Designing DECAP in nanotechnology designs provides many challenges. In this paper first it is shown that all of these challenges are functions of the DECAP channel length. Then, we propose a method for optimizing the channel length of MOS DECAPs. The technique is applied to 45nm and 32nm technology nodes and the results are extracted using HSPICE simulations. The results show that the optimum channel length of MOS DECAPs depends on the technology node and operating frequency. Finally, based on the results, two optimum DECAP configurations which provide trades off among area and gate leakage for different applications in nanotechnologies are proposed.