Statistical Method For Analytically Calculating BER(Bit Error Rate) Of High-speed Link

Improvements in signaling methods, circuits and process technology have allowed input/output(I/O) data rates to scale beyond 10Gb/s. In order to co-optimize the link architecture, circuits, and interconnect, an accurate analysis of system BER including noise and jitter is crucial in high-speed I/O system designs. Following closely from peak distortion analysis(PDA),the purpose of this project is to develop an algorithm which can use single bit response to forecast eye diagram and BER for a high speed system.This dissertation first introduces the constitution and functions of high-speed link, and then we describe the fundamental blocks of I/O signaling channels and introduce basic I/O interface design. It depicts an overall description of I/O interface design, including various topology options that are often not considered in a traditional signal integrity subject.The characteristics of three different interconnect types, a PCB trace, package trace, and on-chip interconnect, are discussed. It also covers major noise components in high-speed I/O links. The basic physics of these noise components are discussed, along with modeling issues. The simulation and analysis aspect of the channel is introduced subsequently. “Channel Voltage and Timing Budget” reviews conventional voltage and timing budget analysis and pda method. Methodologies for balancing system voltage and timing budget are explained in detail to help ensure system robustness in high-volume manufacturing.In this dissertation, a detailed analysis of statistical method for analytically calculating BER(bit error rate) of High-speed Link is introduced. With Linear time-invariant(LTI) theorems used regularly, coupling with the statistical signaling and circuit theorems,statistical signal analysis methods based on probability density function(PDF),cumulative distribution function(CDF),and the corresponding convolution operation are introduced to calculate BER computationally,to determine ISI,noise,and signaling performance for both the link system and the subsystems within it. We review the BER calculation methodology based on linear system modeling of the noise and jitter in Tx、channel and Rx. For a LTI link system,the analog waveform including the voltage impairments of useful signal and impairments(ISI / Crosstalk etc) at the input to the decision slicer of the receiver can be calculated at the decision point.Once the overall joint PDF is available, tail probability can be easily calculated to give BER. A detailed analysis of the modeling method of ISI PDF、crosstalk PDF is introduced to predict the BER performance of high-speed link. Voltage impairments(ISI / Crosstalk etc.) are typically characterized in from of S-parameters in frequency domain or using form of pulse response(or step response) in time domain. PDF of all impairments are convolved to obtain the final PDF. We acquire SBR response by merging the step response waveform files simulated by HISPICE. The simulators calculate the BER distribution plot by convolving the probability density function(PDF) of all individual cursors of the SBR response. On this basis, the realization of DQ BER Eye diagram based on statistical method was given in the end. This method enables fast BER distribution simulation of serial link transceivers that include channel and circuit imperfections, such as Inter Symbol Interference、crosstalk and other noise.