Improved Statistical Link Path Analysis Considering Both Channel ISI and Supply Voltage Fluctuations

Abstract

The statistical analysis method is improved to consider both the channel ISI and the supply voltage fluctuations for accurate estimation of BER. In an I/O link using a linear buffer, the pull-up/down transition with the supply and ground voltage fluctuation can be separately analyzed as the step pulse response and the response due to alternate supply and ground fluctuations. The step pulse response of the channel is simply obtained by transient simulations, whereas the response due to the supply and ground fluctuations is computed from the frequency harmonics of the fluctuations using the frequency-domain channel model. With the channel response due to the supply fluctuations, the PDFs of the amplitude variation can be solved through analytical probability calculations. The PDF of the channel response due to supply fluctuations can be effectively combined with the ISI PDF obtained from the step response, which can provide the accurate total statistical eye and BER.