[time-nuts] Frequency Distribution Design Basic Module

Charles Steinmetz csteinmetz at yandex.com
Fri Aug 28 13:53:06 EDT 2015

Luciano wrote:

>As for the amplifier the big job was finding the balance between the
>polarization parameters, harmonic distortion and output power.
>Many distribution amplifiers on the market have a Po max of + 13dBm
>and this limit does not seem appropriate for this century.

I'm not aware of any instrument that needs a reference signal of more 
than +13dBm (= 1Vrms), and most will happily accept much less than 
that with no reduction in performance -- so I see no reason why a DA 
with a maximum undistorted Po of +13dBm should be considered inadequate.

What does seem inadequate for this century is the distortion 
specification of your amplifier.  -45dBc is pretty poor by today's 
standards, and such high distortion generates additional phase noise 
when the signal is AC-coupled and/or DC-restored, and when the client 
instrument uses a zero-cross detector or other circuit that is 
sensitive to the symmetry of the waveform.  These days, it is not 
difficult to build a 1-10MHz DA with distortion products more than 
65dB below a +13dBm output signal, either discrete or integrated.

Best regards,


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