An integrated circuit (IC) package is described. The IC package includes a package substrate, composed of a substrate core, a first power rail on a first surface of the substrate core, and a second power rail on a second surface of the substrate core. The IC package includes a logic die supported by the second power rail on the second surface of the substrate core. The IC package includes passive devices within the substrate core. Each of the passive devices has a first terminal and a second terminal opposite the first terminal. The first terminal of each of the passive devices is directly coupled to the first power rail, and the second terminal of each of the plurality of the passive devices is directly coupled to the second power rail. The IC package includes package bumps on the second power rail on the second surface of the substrate core.