Accurate estimating simultaneous switching noises by using application specific device modeling

In this paper, we study the simultaneous switching noise problem by using an application-specific modeling method. A simple yet accurate MOSFET model is proposed in order to derive closed-form formulas for simultaneous switching noise voltage waveforms. We first derive a simple formula assuming that the inductances are the only parasitics. Through HSPICE simulation, we show that the new formula is more accurate than previous results based on the same assumption. We then study the effect of the parasitic capacitances of ground bonding wires and pads. We show that the maximum simultaneous switching noise should be calculated using four different formulas depending on the value of the parasitic capacitances and the slope of the input signal. The proposed formulas, modeling both parasitic inductances and capacitances, are within 3% of HSPICE simulation results.