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[Amps] Subharmonic

To: <amps@contesting.com>
Subject: [Amps] Subharmonic
From: W8JI@contesting.com (Tom Rauch)
Date: Tue, 21 May 2002 18:05:09 -0400
> The following is a link to an IEEE paper that I found this morning
> which talks about (and references) analog frequency dividers.
> Apparently the application is high frequency (microwave) low power
> systems where digital dividers are not practical:

Specially designed systems that have oscillators phase-locked to f/2 
are not very common accidents Mike. They take a lot of effort to get 
working and special components. I'm not even sure they are practical 
at HF. 

The most important point is conventional amplifier systems, or non-
linear systems like unintentional diode junctions, can not generate 
subharmonics. For example, a conventional transistor operates in a 
low-Q low-impedance system **without** the required low-capacitance 
low-loss high-Q resonant f/2 resonant circuit to pump. Even if you 
had those components, it is very unlikely (probably impossible) to 
pump the circuit with a conventional semiconductor device used in 
PA's.
 
If you read the text of the paper you pointed out carefully you will 
see the author dismisses the parametric divider as being difficult to 
implement, and requiring Hi-Q components that "can not be implemented 
in contemporary silicon technologies". He moves on to better 
concepts.

I wouldn't worry much about seeing one pop up by accident, since they 
are very difficult to intentionally construct.73, Tom W8JI
W8JI@contesting.com 


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