I am considering using the ADCMP600 high speed comparator to detect pulses from a photo diode. The output will be fed to a time to digital converter (TDC) chip and will be part of a laser ranging system. To maximise the timing precision of the system I need to minimise the random jitter in the comparator. Unfortunately the data sheet for the ADCMP600 only gives values for propagation delay dispersion due to variation in overdrive and common-mode voltage. There is no mention of random jitter. I would like to be sure that the random jitter added by the comparator I select will be lower than the maximum allowed by the laser ranging system, however I can't find any TTL output comparators that specify their random jitter contribution. This parameter only seems to be specified for comparators with ECL/PECL/LVDS etc differential outputs.
I suspect that the random jitter of the ADCMP600 might be good enough (I'd like it to be < 1ns rms) given that in comparators that do have a spec for random jitter it is typically much lower than both the overdrive and propagation delay dispersion (eg for ADCMP561/562 random jitter is 1ps, OD dispersion is 75ps and CMV dispersion is 10ps). If I assume a similar relationship for the ADCMP600 which has OD dispersion 1.2ns and CMV dispersion 200ps then random jitter would be something like 20ps rms. But is this a valid assumption?
Can anyone help?
Cheers
Josh
