Time-Domain Analysis And Decoupling Design Of Power Distribution Network

With the development of digital integrated circuit manufacturing technology,the high speed systems operate with a clock frequency of more than several gigahertz and voltage of below 1V and transient current of up to tens of amperes,which will not only further reduce the absolute tolerance of the ripple noise in the supply voltage and cause signal/ power integrity problems and electromagnetic radiation problems,but also put forward more stringent requirements to power distribution network(PDN)design.The analysis and design of power distribution network is mainly concentrated in the frequency domain in the early research,and the representative method is the decoupling design method of power distribution network based on frequency-domain target impedance.The frequency-domain analysis of power distribution network is a steady-state analysis process under the statistical concept,while the behavior of the power distribution network to deal with the current excitation is a short-term transient response process.So the PDN frequency-domain design method ignores the transient characteristics of PDN and current excitation and regards voltage noise as a DC level,which will lead to over design problems.Relevant scholars have put forward the time-domain analysis and design methods of PDN.The decoupling design method of power distribution network based on the power delivery provides a new idea for the study of the power distribution network decoupling design in the time domain,but the relevant parameters cannot be directly obtained from the capacitance data manual,which will extend the design cycle and reduce the operability.A decoupling capacitor selection method based on maximum time-domain transient noise in this paper is proposed to solve the over design problem caused by the traditional decoupling design method based on the frequency-domain target impedance and the poor operability problem caused by the existing time-domain decoupling design method of power distribution network.According to the analysis and research of the current form in the board level,the switching current can be approximated to the step current with the rising edge under the influence of the on-chip and on-package decoupling capacitors.Then the connection between the step current in board level and the triangular pulse is set up,so that the maximum time-domain transient noise can be deduced by the time-domain transient impedance and the step current in board level,and that the decoupling time range and the decoupling time point can be obtained by analyzing.In addition,the capacitor selection method based on the time-domain property of decoupling capacitor is proposed by the research of the time-domain transient impedance curve of decoupling capacitor;finally,a set of complete time-domain decoupling scheme is summarized.The correctness and superiority of the decoupling capacitor selection scheme proposed in this paper are verified by Matlab software and ADS simulation software.