Analysis of crosstalk noise on parallel traces with nonequivalent lengths

The authors aim at the composition of connection rules in the design of pri nted circuit boards, and this paper discusses crosstalk noise between paral lel traces with unequal lengths. A model is formed for a general circuit co mposed of logic ICs and traces, and the induced noise is examined by varyin g the coupling point. The measurement and calculation results reveal that t here is a large dependency on position. The crosstalk noise is evaluated mo stly by simulation, by varying the active and nonactive sides of the parall el traces, the direction of the signal, and the position of coupling. The r esults obtained from the constructed model are as follows. (1) It is better that the signals have the same direction. (2) It is better that the signal source positions are closer. It is verified by observation of the waveform that the dependency on the coupling position is due to mutual cancellation of the inductive crosstalk. (C) 2001 Scripta Technica.