[time-nuts] sine to square wave circuits - performance data?

John Ackermann N8UR jra at febo.com
Wed Oct 4 13:22:45 EDT 2017


The inductor in the T2-Mini is nothing special.

On Oct 4, 2017, 12:57 PM, at 12:57 PM, Attila Kinali <attila at kinali.ch> wrote:
>On Wed, 4 Oct 2017 12:02:35 +1300 (NZDT)
>Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
>
>> I could measure the PN of the TAPR variant of the Wenzel circuit
>> as well as the PN of the comparator based circuit (with CMOS output
>buffer).  
>
>
>BTW: one thing that has been bothering me with the TAPR variant of the
>Wenzel circuit is the 100µH inductor in the tail of the diff-pair.
>As it presents an impedance of approximately 6k at 10MHz it is cruical
>to the working of the diff-pair (which would otherwise be just two
>independent transistors). But I was unable to find a 100µH inductor
>with a self-resonance frequency significantly higher than 10MHz.
>Quite to the contrary, most seem to mingle around 1MHz. This poses
>two questions:
>
>1) does the TADD2 mini use a special inductor?
>
>and
>
>2) Given the 100µH inductor has an SFR somewhere in the range of 1-5MHz
>and is likely to have significant core losses around and/or above
>10MHz,
>doesn't this limit the performance of the circuit quite significantly?
>
>I have been thinking of replacing the inductor with a current source
>(simple current mirror) and at least in the spice simulations it looks
>decent. No idea of the noise performance, though.
>
>			Attila Kinali
>-- 
>It is upon moral qualities that a society is ultimately founded. All 
>the prosperity and technological sophistication in the world is of no 
>use without that foundation.
>                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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