Ken Kundert wrote on Oct 10th, 2006, 10:27pm:The 0.35 number comes from assuming the produces a Gaussian response (it looks like a Gaussian filter). It is the 10%-90% risetime. See
http://en.wikipedia.org/wiki/Rise_time. I found this by typing "Rise time 0.35 bandwidth" into Google. An actual derivation for the single pole case is given in
http://freespace.virgin.net/ljmayes.mal/circuittheory/Riserc.htm.
I am not sure where the factor of 0.41 comes from, but my best guess is that it is the rise time of a 2nd order maximally flat envelope delay (bessel) filter.
-Ken
Hi Ken,
Thanks for the help.
You's are right also on the explaination on the 0.41 coefficient, since I found the note in th edata sheet as below
"The conversion factor for the rise time to bandwidth is 0.41 since the HFBR-24x6 has a second order bandwidth limiting characteristic."