  The performance of two implementations of digital real-time interpolating
constant fraction discriminator algorithms with respect to fast-timing lifetime
measurements are investigated. The implementations integrated in two different
digitizers were evaluated in terms of the effects of tuning parameters of the
digital CFDs and the influence of different input amplitudes on the time
resolution and time walk characteristics. Reference is made to the existing
analog standard of fast-timing techniques. The study shows, that the timing
performance of both modules is comparable to established fast-timing setups
using analog constant fraction discriminators, but with the added benefit of
digital processing. Both digitizer modules were found to be highly effective
and user-friendly instruments for modern fast-timing requirements.
