[sdiy] All-pass filters, was: Screwing with Square Waves

Phil Macphail phil.macphail at liivatera.com
Fri Nov 1 16:10:55 CET 2013

That depends on what you want - do you want a 90-degree shift on the harmonics too? If so then a polyphase network will do that. There is a trade-off between bandwidth, ripple and number of stages so these days they are probably best implemented digitally.


Sent from my iPhone

> On 1 Nov 2013, at 13:45, "cheater00 ." <cheater00 at gmail.com> wrote:
> Hi,
>> On Thu, Oct 31, 2013 at 7:02 PM, Donald Tillman <don at till.com> wrote:
>> Folks,
>> Please enjoy an article I just wrote about some strange and beautiful aspects of Square Waves:
>>    Square Wave Variations
>>    http://www.till.com/articles/squares/index.html
>> (This presentation relies heavily on the MATHML feature of modern browsers. I'm interested in hearing of any cases where it doesn't work correctly.)
>>  -- Don
> I've been looking into phase and frequency shifts in standard waves
> for some time now. Does anyone have a practical circuit to perform a
> pi/2 (tau/4) phase-shift on an oscillator waveform?
> Cheers,
> D.
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