Tom
10-17-2002, 02:05 PM
IPC Advanced Study Guide Page Reference: Pages 237, Section 4.9
Crosstalk is the transfer of energy between adjacent circuit conductors, via capacitive and inductive coupling. The energy from the "source" conductor becomes superimposed on the "receptor" circuit’s conductor, leading potentially to malfunction of the logic being driven. In order to have crosstalk occur, there must be a coupling between an active line, carrying the signal, and a passive line which, theoretically, is not supposed to have any signals travelling in the conductor. This coupling occurs when the source and receptor route in parallel, on the same or adjacent layers, for extended lengths.
In the example of two adjacent uniform signal conductors, the coupling between the two is caused by mutual inductance and mutual capacitance respectively. Signals introduced into the active conductor will be induced into the passive conductor via electromagnetic fields that accompany the travelling signal on the active line. Signals induced into the receptor line are coupled in both directions, causing crosstalk energy at both ends. The coupled signals going toward the far end are called "forward" crosstalk. The coupled signals coming back to the near end of the receptor line are called "backward" crosstalk.
Crosstalk is the transfer of energy between adjacent circuit conductors, via capacitive and inductive coupling. The energy from the "source" conductor becomes superimposed on the "receptor" circuit’s conductor, leading potentially to malfunction of the logic being driven. In order to have crosstalk occur, there must be a coupling between an active line, carrying the signal, and a passive line which, theoretically, is not supposed to have any signals travelling in the conductor. This coupling occurs when the source and receptor route in parallel, on the same or adjacent layers, for extended lengths.
In the example of two adjacent uniform signal conductors, the coupling between the two is caused by mutual inductance and mutual capacitance respectively. Signals introduced into the active conductor will be induced into the passive conductor via electromagnetic fields that accompany the travelling signal on the active line. Signals induced into the receptor line are coupled in both directions, causing crosstalk energy at both ends. The coupled signals going toward the far end are called "forward" crosstalk. The coupled signals coming back to the near end of the receptor line are called "backward" crosstalk.