Stephan Sandenbergh wrote: > 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 > > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Stephen
Use a Wenzel style odd order multiplier to multiply by 5 after a frequency doubler. For the frequency doubler either use a diode frequency doubler followed by an amplifier or a JFET push-push pair with common source RF feedback as a frequency doubler. The JFET frequency doubler will have very low phase noise if designed properly. For circuit see: http://www.febo.com/time-nuts/Bruce_Griffiths/JFET_frequency_doublers It is also possible to use a pair of bipolar transistors in a pushpush doubler with common emitter RF feedback, the phase noise will also be very low, however biasing the bipolar transistors is a little more difficult than biasing a pair of FETS. Bruce _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
