Optimal placement of decoupling capacitors on PCB using Poynting vectors obtained by FDTD method

This paper describes the searching method for positions of decoupling capacitors on the printed circuit board (PCB). In this method, first, the distributions of electromagnetic field between power and ground planes in the time domain are simulated, using FDTD method. Next, the distribution of Poynting vectors in the frequency domain is investigated, using fast Fourier transform (FFT). Furthermore, this method finds the optimal location of decoupling capacitor so that the Poynting vector is the highest. Finally, we analyze the distribution of magnetic field emission above the signal plane in the x and y axes in the specified range of frequency and verify the validity of our method.