Incremental Power Impedance Optimization Using Vector Fitting Modeling

One effective way to reduce power ground network noise is to add decoupling capacitors, but this method changes the impedance and natural frequency. Traditional simulation requires re-simulating the whole circuit, which is time-consuming. This paper presents a fast impedance curve and natural frequency computation algorithm, based on vector fitting modeling with incremental value of decap. The new method fits several sampling data in an impedance curve with a rational function. Therefore, the impedance at other frequencies would be easily interpolated. Moreover, vector fitting computes poles accurately and thus finds natural frequencies. Experiments show that the results of this method are accurate and the algorithm complexity is much lower than with traditional method.