We report on a multifunctional optoelectronic radio frequency attenuator for millimeter wave applications, designed in a multilayer thin-film multichip module technology on high resistive silicon. Insertion loss measurements of a coplanar waveguide line under illumination demonstrate a contrast of 40 dB at 100 GHz. The interaction between the radio frequency signal and the photoinduced conductivity is modeled with 3D electromagnetic solvers