The effect of higher order model decoupling capacitors in the design of a power delivery network

Decoupling capacitors are widely used in power delivery network (PDN) design to mitigate switching noise from the integrated circuit (IC). Besides, they also provide a low-impedance path to shunt the transient energy to ground at the IC source. Since a real capacitor includes both parasitic inductance and resistance associated with the interconnection and package of the capacitor resulting in an increase in impedance, adequate decoupling capacitances in a PDN design are essential. Often, a capacitor is represented with a higher order model (HOM) of resistance, inductance and capacitance in power delivery simulation. This paper presents the findings from an investigation into the PDN performance using various HOM decoupling capacitors of the same capacitance. The reasons for the different HOM values with the same capacitance include the form factor, manufacturing processes and the operating temperature of the capacitors. From the study, it was found that both the form factor and the differences in the capacitors manufacturing process can cause a significant difference in the impedance profile as well as the voltage droop whereas the operating temperature has a much less impact on the PDN performance.