Artificial extrinsic and intrinsic multiferroic structures were developed in the form of yttrium-iron garnet/barium-strontium titanate bi-layers and manganese-doped barium-strontium titanate films with a relatively high doping rate in the range of 10-20 mol%. For the experimental investigations, the planar capacitors were formed on the surfaces of the structures and the capacitance-voltage characteristics were measured. Structural characterization of the samples under study was based on X-ray diffraction analysis and film-substrate interfaces were investigated by X-ray photoelectron spectroscopy. The relative dielectric permittivity, dielectric loss tangent, and electric field tunability of the samples were measured in a temperature range from 77 to 300 kappa. The additional 6 and 3 % tuning of the dielectric permittivity by external magnetic field of 2000 Oe was demonstrated for the extrinsic and intrinsic structures, respectively.