The effect of bus driver devices on transmission line emission

In a number of large computing systems of similar design, interunit cables within the systems were found to be responsible for much of the radiated emission. A bench-level experiment revealed that the noise itself was a function of common-mode current spikes, brought about by the skew between the outputs of clocked differential drivers. Significant improvements in systemwide emissions were seen after replacing those driver devices with others that had less skew.<>