Abstract: From the impulse response of a digital serial communication channel, this paper gets the mathematic expression for the data dependence jitter(DDJ) crossing unique threshold. An induction method is found to search for the special codes which makes DDJ unilaterally increase or decrease and calculate the extremum of DDJ. In contrast with the method using a lot of random codes to search for the peak-peak value of DDJ, this method can calculate this value directly with less computation complexity. The analytical result and simulated result are compared according to a second order system and this method need only compute no more than 20 codes to reach the precision of simulating 105 random codes. This method also can be used to analyze the other jitter components.

Key words: data dependence jitter(DDJ), inter-symbol interference (ISI), eye diagram