Phase Self-Correcting LP Filter
in [Design]
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From: Glenn Kenroy on 20 Jun 2010 03:18 I am looking for a 60Hz active low pass filter, either discrete or IC, that will automatically compensate for the phase delay it imposes. IOW so that the LP filtered signal matches in phase that of the original input one. The type or order of the filter is not relevant at this stage. Can anyone please provide a circuit or technical reference for this application? Glenn Kenroy
From: MooseFET on 20 Jun 2010 10:44 On Jun 20, 3:18 pm, glennken...(a)radcliff.com (Glenn Kenroy) wrote: > I am looking for a 60Hz active low pass filter, either discrete or IC, > that will automatically compensate for the phase delay it imposes. > > IOW so that the LP filtered signal matches in phase that of the > original input one. > > The type or order of the filter is not relevant at this stage. > > Can anyone please provide a circuit or technical reference for this > application? > This sounds like a job for the PLL. If you have a signal you can lock it onto, they do this sort of thing easily. If you want no phase shift in a linear filter, you need a band pass filter. You can contrive a low pass filter to have exactly 180, 360 or some multiple degrees of phase shift at your working frequency and call this no phase shift if you want but other than that the nature of the universe prevents you from making a low pass with no phase lag. > Glenn Kenroy
From: Vladimir Vassilevsky on 20 Jun 2010 11:44 MooseFET wrote: > On Jun 20, 3:18 pm, glennken...(a)radcliff.com (Glenn Kenroy) wrote: > >>I am looking for a 60Hz active low pass filter, either discrete or IC, >>that will automatically compensate for the phase delay it imposes. > If you want no phase shift in a linear filter, you need a band pass > filter. So, if I take one bandpass filter at 60 Hz, then connect another bandpass filter at, say, 55 Hz, in parallel, then another at 50, 45,40 and so on, so forth to zero Hz... this will make a lowpass filter with no phase shift :))))) VLV
From: MooseFET on 20 Jun 2010 12:40 On Jun 20, 11:44 pm, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: > MooseFET wrote: > > On Jun 20, 3:18 pm, glennken...(a)radcliff.com (Glenn Kenroy) wrote: > > >>I am looking for a 60Hz active low pass filter, either discrete or IC, > >>that will automatically compensate for the phase delay it imposes. > > If you want no phase shift in a linear filter, you need a band pass > > filter. > > So, if I take one bandpass filter at 60 Hz, then connect another > bandpass filter at, say, 55 Hz, in parallel, then another at 50, 45,40 > and so on, so forth to zero Hz... this will make a lowpass filter with > no phase shift :))))) Actually, no it won't because you left out the bandpass filter at 57.923145067Hz. You need to add that one to the list and then check it again. :)
From: VWWall on 20 Jun 2010 13:06
MooseFET wrote: > On Jun 20, 11:44 pm, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: >> MooseFET wrote: >>> On Jun 20, 3:18 pm, glennken...(a)radcliff.com (Glenn Kenroy) wrote: >>>> I am looking for a 60Hz active low pass filter, either discrete or IC, >>>> that will automatically compensate for the phase delay it imposes. >>> If you want no phase shift in a linear filter, you need a band pass >>> filter. >> So, if I take one bandpass filter at 60 Hz, then connect another >> bandpass filter at, say, 55 Hz, in parallel, then another at 50, 45,40 >> and so on, so forth to zero Hz... this will make a lowpass filter with >> no phase shift :))))) > > Actually, no it won't because you left out the bandpass filter at > 57.923145067Hz. You need to add that one to the list and then > check it again. :) > The components get pretty big for the one at zero Hertz! |