frankrose
Advanced Member level 3
I don't see this criteria there, however it makes sense, KlausST mentioned phase shift earlier maybe, but Butterworth doesn't seem too bad I think. In the pass band the group delay is not so dramatical if the output signal's bandwidth is much smaller than 40kHz, and what is placed down now on the PCB I found it as a trade-off.But Butterworth doesn't meet the linear phase requirement in post #18. A 40 kHz Bessel filter would, but it needs f0=60 kHz Q=0.5.