The subject of this work is the design of a LiNbO3 electro optic tuned bragg filter to be used as an amplitude modulator. We begin describing the main elements of the device: wave guides, Bragg gratings, annealing proton exchange (APE), diffusion process and the Pockels effect. Next we analyze in detail the realized waveguide and simulate the grating, developing a fabrication methodology for building the Bragg modulator by niobate core etching. Finally, we evaluate the performance of the modulator, using the finite element method analysis. The more relevant results concern the modulator characteristic and the annealed proton exchange process parameters. These parameters, not yet analytically determined, have been simulated to relate the proton concentration with the refractive index distribution and the propagation modes in the guide.