wordave
Member
I've been working on a set of multifeedback filters for a preamp I am designing and I've encountered a problem. The 100Hz filter I have designed is unstable. I've attached the frequency response and phase response tests as well as the schematic. I've also attached the phase shift vs frequency graph supplied in the TL074 data sheet (Op amp used in the tests).
Both the phase response graph and TL074 show different phase shifts in the <100Hz region. This is what I think is to blame for a unstable frequency response.
One question ... What is going on?! I've really exhausted my knowledge on this subject and would appreciate any insight anyone may have. I'm 99% sure its phase causing the problem, just not sure why.
Download the files here: http://www.inverseaudio.co.uk/Filterissues.zip
Both the phase response graph and TL074 show different phase shifts in the <100Hz region. This is what I think is to blame for a unstable frequency response.
One question ... What is going on?! I've really exhausted my knowledge on this subject and would appreciate any insight anyone may have. I'm 99% sure its phase causing the problem, just not sure why.
Download the files here: http://www.inverseaudio.co.uk/Filterissues.zip