Simple and fast method of on-board decoupling capacitor selection and placement

Simple and fast method of on-board decoupling capacitor(decap) selection and placement is introduced, which can be performed easily based on math tools or general EDA tools. This method is based on simple estimation formula of decap models, and can decide whether specific area needs some decaps or not, and what are the values. It can both simplify the process and achieve good results when finding the optimal solution. To perform this method, first, prepare the power network S parameters of PCB; second, set up the optimization topology, variables and goals; then perform the optimization by some optimizer; finally, we will get the suggested selection and placement scheme of decaps with the optimal impedance profile. Detailed applications of one example case demonstrate the proposed method with reasonable goals achieved.