[sdiy] BODE Frequency Shifter

Quincas Moreira quincas at gmail.com
Mon Nov 5 17:18:08 CET 2018


Thanks Bernie!

On Thu, Nov 1, 2018 at 8:06 PM Bernard Arthur Hutchins, Jr <
bah13 at cornell.edu> wrote:

> It is good that Atsushi Maeda found the difficultly to be only that of
> misidentifying a component.  90-degree PDNs are very INSENSITIVE to
> component tolerance variations (because they have only real-valued poles).
>  A moderate amount of care should assure a near-nominal performance –
> they just work – no tweaking.
>
>
>
> An exception to this rosy picture occurs when we use an extremely large
> bandwidth to minimize end phase errors – say 5000:1.     The poles have a
> corresponding spread and so do the RC products of the individual sections.
> In attempting to keep resistors in a range of perhaps 5.1k to 100k,
> capacitors may spread outside a corresponding desired spread range of
> perhaps 330 pfd to 0.05 microfarad (too small means stray capacitance
> matters, too large that caps are physically too large).  Happily I found
> some 30 years ago that by pairing the poles, largest to smallest, using
> 2dn-order secions nsead of first, the spread range is reduced to near unity.
> See:
>
>
>
> http://electronotes.netfirms.com/EN168-90degreePDN.PDF
> LARGE SPREAD OF CAPACITOR VALUES; - Netfirms
> <http://electronotes.netfirms.com/EN168-90degreePDN.PDF>
> electronotes.netfirms.com
> THE DESIGN OF WIDEBAND ANALOG 90° PHASE DIFFERENCING NETWORKS WITHOUT /\
> LARGE SPREAD OF CAPACITOR VALUES;-by Bernie Hutchins INTRODUCTION: The
> design of wideband 90° phase differencing networks is fundamental to the
>
>
>
> This discussion along with several related entries is on the Electronotes
> site as misc. items.   As a bonus, you cut the number of op-amps  in half.
> Only reasonable way to design these – or so it seems to me.
>
>
>
> Bernie
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>


-- 
Quincas Moreira
Synth Diy Guy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20181105/8b1efef6/attachment.htm>


More information about the Synth-diy mailing list