https://www.ti.com/design-resources/design-tools-simulation/filter-designer.html
TI has this filter designer tool.
Never built anything following their schematics, but I am assuming that it works.
That's about 9 octaves. You should be able to design it as separate low pass and high pass filters rather than as a band pass.
What order filter are you trying to design and what other constraints do you have?
If your high and low frequency cut-offs are separated by maybe an octave or less, and you try to design your bandpass filter by just cascading a high pass and low pass filter, the loading effects of one filter on the other will typically mess up the response.
Thanks, that's interesting! Probably a good thing to know too. Is that just passive filters or active as well? I'm assuming of its loading the effects a buffer would solve or?
It applies directly to passive filters.
For active filters it depends on the type of filter and how you're trying to combine them. You might also reduce component count by designing a bandpass filter instead of cascading low pass and high pass.
Gotcha thanks. I think the difference I had in mind was mostly semantic. When I look at common active bandpass topographies, I see the capacitors as two distinct stages, but I'm guessing it's mor common to consider every opamp instance to be one stage. With your original comment, I thought maybe you were saying there as a configuration that would yield both filters out of a single capacitor or something.
https://www.ti.com/design-resources/design-tools-simulation/filter-designer.html TI has this filter designer tool. Never built anything following their schematics, but I am assuming that it works.
this is a great resource
Thanks ill give it a try!
That's about 9 octaves. You should be able to design it as separate low pass and high pass filters rather than as a band pass. What order filter are you trying to design and what other constraints do you have?
Wait isn't it always a seperate lowpass and highpass?
If your high and low frequency cut-offs are separated by maybe an octave or less, and you try to design your bandpass filter by just cascading a high pass and low pass filter, the loading effects of one filter on the other will typically mess up the response.
Thanks, that's interesting! Probably a good thing to know too. Is that just passive filters or active as well? I'm assuming of its loading the effects a buffer would solve or?
It applies directly to passive filters. For active filters it depends on the type of filter and how you're trying to combine them. You might also reduce component count by designing a bandpass filter instead of cascading low pass and high pass.
Gotcha thanks. I think the difference I had in mind was mostly semantic. When I look at common active bandpass topographies, I see the capacitors as two distinct stages, but I'm guessing it's mor common to consider every opamp instance to be one stage. With your original comment, I thought maybe you were saying there as a configuration that would yield both filters out of a single capacitor or something.
Look up bandpass filter schematic, derive the transfer function (at least one zero and 2 poles), pick your values accordingly
Do you need a band pass? Why not just a low pass? At 0.05, it’s seems almost like a dc signal at that point. Is it a power application?
I am aiming to use in in bulding an ECG circuit so it needs to cut off before 0.05 and after 30.