[time-nuts] Square to sine wave symmetrical conversion

[Charles Steinmetz]

Jerry wrote:

>I have been trying to find a way [to] explain how a
>high harmonic oscillator stage is even possible and zip.

Simple.  Use a circuit with way more gain than necessary, and bias it 
so that it goes into saturation at the one end of its voltage 
excursion long before the current gain drops off at the other 
end.  So, its average gain over a whole cycle comprises a pretty 
linear region bounded on the one end by a region of near-zero gain 
due to hard clipping.  Since the gain element loads the resonator 
heavily during the period of saturation, the circuit Q is much less 
than it should be -- so even if you take the output from a relatively 
high-Q node, there isn't enough Q to filter out the high harmonic content.

Lots of commercial oscillator products have been built exactly that 
way, usually with a Tee or Pi output filter with moderate Q (an 
output network of some sort is necessary anyway to match a 50 ohm 
load -- using a Tee or Pi with some Q cuts the harmonics to a dull roar).

Best regards,

Charles