problem with butterworth simulation

[atrac]

I am trying to simulate a butterworth filter, as per Analog Devices application note AN-209.

I captured the first stage (attached multisim file). However, when I simulate, I get some weird result. Looking into the scope, the circuit is oscillating, while bode plot looks sensible but I am not convinced of the cut frequency.

What am I doing wrong?

Thank you.

[AntonisV]

Hello atrac,

have you taken a look at this link?

How to use the Filter Wizard in NI Multisim

http://zone.ni.com/devzone/cda/tut/p/id/5495

[atrac]

Thank you for your reply.

However, I need a different configuration that the filter wizard is not able to replicate, since I need to dinamically change the cut frequency by means of adc's as described in the mentioned application note.

In the meantime I noticed that if I increase R3 and R4 over 10k the cyrcuit does not oscillate any more, however this is not what I expect.

Regards