Minimum phase delay notch filter

[Martin Greaves]

I am considering using a 50Hz active filter such as the first one
illustrated here:

http://www.radio-electronics.com/info/circuits/opamp_notch_filter/opamp_notch_filter.php

However, I would like to keep phase delay to a minimum. Is this a
suitable circuit for this criteria, or is there something more
suitable?

I have heard Bessel filters are superior in this regard, but the notch
is notch as sharp. Has anyone seen an online caluclator for these?

How does the number of poles affect the phase linearity?

Any suggestions?

Martin Greaves

 

[Phil Allison]

"Martin Greaves"

I am considering using a 50Hz active filter such as the first one
illustrated here:

http://www.radio-electronics.com/info/circuits/opamp_notch_filter/opamp_notch_filter.php

However, I would like to keep phase delay to a minimum. Is this a
suitable circuit for this criteria, or is there something more
suitable?

** I you need to avoid phase shifts in the wanted signal then forget using
notch filters altogether.

I have heard Bessel filters are superior in this regard, but the notch
is notch as sharp.

** In general - the phase response of a filter is a function of the
amplitude response.

FFS tell us what you are trying to do so an alternative solution can be
suggested.


...... Phil