This equation contains the power sum FEXT
budget for the connector in the numerator of the second exponent term.
In Figure 9, the S-parameters of insertion loss, return loss, near end crosstalk (NEXT), and far end crosstalk (FEXT
) are shown.
al., 2002) the received power spectral densities (PDSs) of NEXT and FEXT
due to more than one crosstalk disturber for n interfering signals of the same kind become
crosstalk signal is created in a similar manner as the NEXT crosstalk signal (its spectrum is presented on fig.
is dispersed similar to the desired received signal, canceling it can require a significant amount of signal processing hardware.
With a rise time of 25 psec, typical of a high-end PCIe gen II part, and a coupled length of 2", the FEXT
would be about 20%.
The eye-pattern measured from the circuit with the compensated capacitor significantly reduces the jitter due to the improved FEXT
on the circuit.
Far-end crosstalk normalized by subtracting the attenuation of the disturbing pair from FEXT
induced on an adjacent pair.
* Far end crosstalk (FEXT
) is a measure of the amount of signal from a device on one end of the cabling system that couples into an adjacent receive circuit in a device on the other end of the cabling system.
While the influence of near-end (NEXT) crosstalk can be partially limited by using several different frequency bands for both directions (there are several various frequency plans, scenarios, for VDSL2 lines), the influence of far-end crosstalk (FEXT
) cannot be reduced so easily.
IF YOU HAVE ever used a 2D field solver to calculate the far-end crosstalk coefficient (FEXT
) in a pair of microstrip transmission lines--a critical part of every design with surface traces!--you've probably encountered what appears to be a typo or a bizarre result.