Trying to build a multi-stage 120kHz bandpass filter... decided to use multi-feedback topology...
Seems that it amplifies the desired signal alright, but ends up full- swing output (after just one stage) and since it's inverted, the full- swing output feedback ends up cancelling out the input and it collapses back on itself.
I'm no op-amp expert but am ernestly trying to learn.... and I'm stumped on how to procceed...
thanks! ..dane
Schematic? Maybe you could shoot for unity gain in the filter stage and do your amplifying seperately. The filter stage will still provide gain, but only to what you want to hear. Download TI FilterPro, you won't regret it. I've built active filters using it, it works. :-)
:-)
Thanks Anthony. I tried it out and it's working great...
I used some filter design tool the first time around (can't remember which), but I think I may have 'tweaked' it too much and broke it... Going back to FilterPro helped a lot and I'm now back-on-track.
thanks! ..dane
I told ya you'd like it. :-)
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