[time-nuts] FE-5680A clock shaping (sine -> square wave)

ehydra ehydra at arcor.de
Tue Jan 3 06:01:13 UTC 2012



David schrieb:
> I could analyze it on SPICE but I suspect the real world construction
> parasitics will be what limits the performance.  I just sketched it
> out in my notebook but I will see if I can post it somewhere.  Is
> there a quick and dirty online schematic capture site?

Scan it. I will make a LTspice file.


> 
> It is not that complicated being a differential amplifier driving
> complementary pair of emitter followers, a pair of voltage clamps, and
> then a pair of complementary current mirrors configured as
> transconductance amplifiers.

I want to SEE it including all circuit parameters. Thank you.


> 
> When you say symmetry limiting do you mean to prevent second harmonic
> distortion like for driving a mixer?  I was thinking of this more for
> driving a single ended transmission line cleanly while maximizing the
> edge rates and minimizing jitter.  Duty cycle correction could be
> added pretty easily.

Hm. I think second harmonic distortion looks very much like intentional 
symmetric waveform in the first instance. The fun begins if we decide to 
look for equal time distance or equal power for both phases. Interesting.


> 
> The circuit you linked is going to have a little problem since both
> the 2N5769 and the 2N5770 are NPN and the circuit requires a pair of
> PNPs.  Other than that it looks perfect for driving a high level
> mixer.

As far as I know driving a mixer was the circuit intention. I SPICEd it 
with BFR93 types. The circuit has a high reflection coefficient, 
unfortunately. Maybe this is unavoidable and we need a diplexer.

Yes, looks like an typo for having 4 NPNs there. I will clarify this 
with Chris Trask. Thanks.


> 
>> Here is another limiter circuit (by Chris Trask):
>> http://ehydra.dyndns.info/NG/LTspice/Negative%20Impedance%20LO%20Driver.pdf

- Henry

-- 
ehydra.dyndns.info




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