i have designed a simple filter with a operational (a buffer). I have used Simscape (simulink). Now i want to know the response in frequecy (Bode diagrams) of this, my problem is that i do not know how to get diagrams.
Yes, it is possible. You need to linearize the model around an operating point to obtain a state-space representation, from which you can generate a Bode plot. Have a look at the SimElectronics demo entitledSmall-Signal Frequency-Domain Analysis in the help browser, under SimElectronics -> Demos -> Generic Circuits.
There are other resources in the Simscape documentation: