| With the continuous development of high-speed circuit systems,the integration of chips is getting higher and higher,and the speed of signal transmission is getting much faster than before.The influence of power noise on the transmission quality of the passive link and power distribution network is becoming increasingly serious.How to predict the performance of the system in the early design stage and guide the engineering design has become an important research content of signal integrity.Engineers usually evaluate the system performance by eye diagram,but the traditional worst eye patterns analysis method is time-consuming and laborious,which may lead to excessive design.In contrast,the bit error rate eye patterns analysis is simple and efficient,which is more suitable for the performance analysis of high-speed link systems like DDR4.At present,the bit error rate eye patterns analysis mainly considers the influence of passive link.Few people in the industry have done the collaborative simulation on the PDN noise and passive link,or analyze the link error rate under the common influence of the two.Based on the DDR4 parallel high-speed link,this paper presents a fast simulation of the full link error rate eye patterns,and analyzes the influence of the passive link and PDN noise on the signal transmission.In this paper,the DDR simulation experiment platform is set up first.Secondly,the influence of passive link and PDN noise on transmission signal is calculated respectively.The influence of DDR4 passive link mainly includes inter-symbol-interference and crosstalk.After the ISI and crosstalk data are obtained by the SPICE simulation software,the probability distribution of ISI and crosstalk is obtained by unit impulse response method and step response method.Then the probability distribution of PDN noise is calculated.Selecting the pseudo random code of the appropriate digit as incentive,the PDN noise is simulated through SPICE software,and the probability distribution of PDN noise is calculated using statistical method.Finally,the total probability distribution is obtained through convolution of the probability distribution of ISI,crosstalk and PDN noise,thus the bit error rate eye pattern is calculated.PDN noise and passive link collaborative simulation is the innovation of this paper.At the end of this paper,the high-speed link error rate analysis algorithm which considers the power distribution network is compiled into an executable BER_Tools software.The interface and the usage method of BER_Tools are introduced in detail,and the feasibility of the algorithm is verified by several examples.Compared with the traditional method of eye pattern analysis,our algorithm can calculate the BER eye diagram faster and save more time,and the algorithm takes into account the influence of passive link and power distribution network at the same time,which has great guiding significance for practical engineering development. |
