Efficient Method for Modeling of SSN Using Time-Domain Impedance Function and Noise Suppression Analysis

In this paper, a new method is proposed to model the simultaneous switching noise (SSN) using time-domain impedance function, which is based on the rational function in time domain. The time-domain impedance function of a power delivery network (PDN) is calculated by approximating the impedance frequency response of a PDN with a rational function, and the SSN is calculated based on switching current characteristics, which is verified by advanced design system, Hspice and measurements. Based on time-domain impedance function, the SSN suppression is also investigated, and it is found that the SSN produced by periodic switching current can be suppressed through adjusting the periods of time-domain impedance function and switching current, and a principle for random switching current is also given to prevent the occurrence of the worst case of SSN in circuit design.