We had these in the 80’s for window margin tests on clock,data to detect a track’s margin of data error free they were selectable delay lines with an ECL digital mux with +/-2ns to +/-50ns to allow transitions inside that data window. This way BER testing for soft and hard errors could be accelerated by many orders of magnitude depending on noise slope/dB of SNR and jitter. I could easily measure pattern dependent margins to compute asymmetry, supply sensitivity, temp, vibration, media margin, defect mapping etc etc. In HDD’s
One tool was so simple that you simply inserted it in the system to self clock pseudorandom bit shift early and late by tapped delay lines which it mixed to add jitter until the system reported an error. Thus the SNR could be interpolated or interference made more sensitive.
It would help greatly to explain your application and preferred interface with as much detail as possible.