Hi Folks, thank you very much for your kind explanation and hints regarding micro phase steppers. I have not been aware of the 'linear ramp method' for that purpose. I have seen linear ramps to be used in sub-clock interpolation schemes in time-to-digital-converters as well as in a certain kind of high speed adc (Wilkinson) being used in nuclear pulse height spectroscopy due to its low differential non-linearity.
I imagine very well how a dac driven constant current source sourcing or sinking a small capacitor in conjunction with a comparator may give a variable slope linear ramp allowing very fine delay steps. However, even with a arrangement like that, i would expect the device to have a minimal delay of say the propagation delay of the comparator plus one or two gates in a current semiconductor technology, so '0' to x.xxx ns is perhaps a bit too optimistic??? Or have those high tech guys some 'faster than light' technology available for compensation of propagation delays??? If ready to go integrated circuitry is available like the MAXIM parts, this is pretty much like a invitation to use them but i will remember Tom Buehl's suggestion and check their precision first before i use them in a real project. I have not checked Tom Clarke's links due to my slow private ISDN line (I live in a region of Germany where we have more cows than humans per square kilometer. We will be lucky to get DSL at the end of the year). Will check that the next day at my working place where we have a DSL-3000 line. Thank you all for your help, this group is definitely the 'high signal-to-noise ratio place' that John is asking for! Ulrich Bangert, DF6JB _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts