[time-nuts] 10 MHz -> 16 MHz clock multiplier

[paul swed]

I think the thread branched and as I recall started something like this.
Someone needed a "Simple" 16 Mhz for a uproc made from a 10 Mhz source.
Two reasonable answers were given.
Injection locked oscillator
Typical div and mult/filter.
A third and kind of interesting for me a Ti chip soic digital pll.
Then the thread went a whole bunch of directions.
Wonder if who ever needed an answer got the answer?
Regards
Paul
WB8TSL

On Fri, Jan 4, 2013 at 7:18 PM, <EWKehren at aol.com> wrote:

> How about getting back to basics.
> Is it a one off, if production how many and what are the specification
> requirements? Otherwise on this list it can go on for a year.
> Bert Kehren
>
>
> In a message dated 1/4/2013 6:11:14 P.M. Eastern Standard Time,
> wlfuqu00 at uky.edu writes:
>
> At 07:51  PM 1/4/2013 +0000, you wrote:
> >My question is about the phase noise of  the final 16MHz signal.  Do
> > > crystal filters "clean up" the  signal.  It seems that after several
> > > 16MHz crystals in  series the output should look a lot like an XO.
> >  >
> >
> >For offsets out to 100 Hz or so, using a crystal filter  will cause
> >the signal to have the same flicker noise that an oscillator  built
> >with that crystal would have.  Thus don't try to use some  junky
> >clock crystals to make a crystal filter as described in  numerous
> >ham radio articles about receiver IF filters.  If you  have a
> >residual phase noise measurement system like the Agilent  E5505A
> >and a very low flicker noise source, you can actually measure  your
> >filter crystals.  Of course, the crystal time base in the  source
> >has to be better than the crystals you are measuring.  You  also
> >have to avoid overdriving the crystal.  This will require a  low
> >noise buffer amplifier to bring the signal back up to a  high
> >level.
> >
> >Now after considering all that, crystal  clean up filters don't
> >sound like such a great idea unless you have no  alternative.
> >
> >Rick Karlquist N6RK
> Flicker noise  (1/f ) noise would be introduced by an amplifier and not
> by the  filter.  I am only suggesting ways to multiply the frequency.
> You  could use LC filters or a crystal filter. Using 3 doublers would
> do the job  just as well. Naturally if you are concerned about flicker
> noise
> you could  simply make the 2 MHz signal higher in amplitude before
> selecting
> the 8th  harmonic.
> I was not saying your going to clean up a good  crystal oscillator with a
> crystal filter. I though you were talking about  generating 16MHz from
> 10MHz
> in a clean way. Using a microcontroller or even  most synthesizers
> techniques would make
> it even worse.
> The PTS synthesizers have fairly good phase noise when they use
> frequency  multiplication,
> division, mixing, comb generation and filtering on the most  part to
> achieve
> low phase noise.
> The later models use a DDS at the  lower frequency levels but do have
> greater phase noise
> close to the  carrier.  In fact in the SGA unit the reference input goes
> thru a  transistor ( to distort it)
> and then into a series 10MHz crystal filter so  that it can accept either a
> 5 or 10 MHz input.
> The  crystal also helps filter out any birdies that may be on the
> reference  signal.
> The filter should be fairly high Q since it has 47 Ohm drive  impedance and
> 100 Ohm load impedance.
> 73
> Bill  wa4lav
>
>
>
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