[time-nuts] Micro Phase Stepper: Thank you!
df6jb at ulrich-bangert.de
Tue Jul 19 14:55:13 EDT 2005
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
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
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