Published by Eric Bogatin on 16 Sep 2012 at 09:03 am
Cross talk between two single-ended or two differential channels can be a problem which causes a product to fail. While a typical required signal to noise ratio (SNR) for some systems may be as low as 20 dB, in mixed signal applications it may be as high as 60 to 80 dB and in lossy channels, it may need to be above 45 dB.
To various extents, the coupling between aggressor and victim channels depends on the signal rise time, coupled lengths, interconnect density and line impedances. But not all system simulators take into account all the couplings which can cause problems. This is why it is sometimes important to measure the channel to channel cross talk.
S-parameters provide a natural way of characterizing cross talk between channels because each term in the S-parameter matrix really describes the coupling of one port into another. When the ports are on different channels, this is really the cross talk between the channels.
In the recently posted article on the Test and Measurement web site, “Use S-parameters to describe crosstalk”, Alan Blankman and I review the properties of S-parameters which make them so suitable to cross talk and some of the features to look for in both the frequency domain and the time domain.
If you care about cross talk, you’ll want to check out this feature article.