[time-nuts] Low noise frequency multiplication
Stephan Sandenbergh
stephan at rrsg.ee.uct.ac.za
Wed Feb 28 18:19:31 EST 2007
Hi all,
How difficult is it to multiply a frequency standard from 10MHz to 100MHz?
I found the recent discussion about amplifying a 10MHz OCXO output from 5dBm
to 15dBm very interesting. Thanks Bruce for sending me that common base
circuit schematics - I had quite a lot of fun simulating it and brushing up
on my electronics and RF knowledge. One down side to that circuit is that
it operates from quite a high voltage (24V) causing quite a lot of
dissipation in the amplifying transistor. When the operating voltage is
lowered the harmonic content increases (as expected), but most of it can be
fixed with an output BP filter as Bruce mentioned.
The other day I stumbled across the following article on Wenzel's website:
http://www.wenzel.com/pdffiles/RFDesign2.pdf
It describes a way in which an analogue odd-order frequency multiplier could
be built cheaply with superior noise characteristics. This circuit that is
described is really simple and quite ingenious. Unfortunately, I would like
to multiply by 10 (an even number) so I still need a way to at least
multiply by 2. Commercial low-noise multipliers are in general much more
expensive than my OCXO. So now I am curious if there is an easy and reliable
way to get a 10MHz sine up to 100MHz without degrading the phase noise.
Regards,
Stephan Sandenbergh
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