[time-nuts] Stepping up the output of an OCXO

Stephan Sandenbergh stephan at rrsg.ee.uct.ac.za
Thu Feb 1 11:00:19 EST 2007

Hi All,


Say for instance you have a 5dBm clean 10MHz sinusoid (such as that provided
by an OCXO). Now you want to run this signal to a device that will take a
minimum of 10dBm and maximum of 15dBm as input. How does one amplify the


The first thing that sprang to mind is a step-up RF transformer. However, it
is impossible to step-up because the following device has an input impedance
of 50ohm. To step it up you'll need a higher input impedance. A step-up
transformer will also mess with the matching.


After Googling a bit I found that another option might be LC-resonance. This
seems like a good idea since resonance is per definition a filter-like


The easiest, of course, would be if there exists some integrated solution. I
browsed through the list of RF gain blocks on the Mini-Circuits site - these
little guys seem perfect for the job. However, the typical situation is that
it amplifies by at least 10dBs while the maximum output of it sits at around
13dBm. 5dBm will thus more than saturate the poor thing.


My final idea is a high speed opamp. I suspect this would add nasty 1/f
noise. Probably the same with a simple RF transistor amplifier. 


Do you guys have any better ideas?  Your thoughts on this are much


Kind regards,


Stephan Sandenbergh







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