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<p>I think an envelope follower with no lag is called a rectifier.</p>
<p>Jokes aside, there are a number of options available but
ultimately it comes down to filtering.</p>
<p>For digital envelope followers, I like to use a simple
exponential average (aka leaky integrator, a first-order IIR
filter) on the fully rectified signal and tune the time constant
to the expected input signal. Generally you want it to be fast,
but not so fast as to track the waveform oscillations, even at say
20 Hz. This makes a computationally very efficient follower with
predictable results.<br>
</p>
<p><br>
</p>
<p>best,</p>
<p><br>
</p>
<p>Martin</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 16/12/2021 01:36, Jean-Pierre
Desrochers wrote:<br>
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cite="mid:003d01d7f215$0904e630$1b0eb290$@oricom.ca">
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Here
is my goal..<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-CA">I need a circuit that will take an AC signal
and will shift level it from<br>
a DC offset extracted from its min & max Peaks..<br>
Ex: Suppose you have steady +/- 5v peak sine wave coming in
this circuit,<br>
The output would be the same waveform but shifted up to
+5vdc. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-CA">So 0 to +10vdc.<br>
That final waveform would be much usable for a 0-5vdc
control voltage input<br>
than the original AC waveform.<br>
Now the challenge is to do the same with a level changing AC
signal.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-CA">In the case of a <u>steady waveform</u> this
‘level shifter’ could be an opamp that would add half of the
peak to peak voltage as an offset DC voltage,<br>
But here I’m looking for something that will be more
versatile<br>
to handle varying level waveform.<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-CA"><o:p> </o:p></span></p>
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