Abstract: A semiconductor package assembly and an electronic device are provided. The semiconductor package assembly includes a base, a system-on-chip (SOC) package, a memory package and a silicon capacitor die. The base has a first surface and a second surface opposite the first surface. The SOC package is disposed on the first surface of the base and includes a SOC die having pads and a redistribution layer (RDL) structure. The RDL structure is electrically connected to the SOC die by the pads. The memory package is stacked on the SOC package and includes a memory package substrate and a memory die. The memory package substrate has a top surface and a bottom surface. The memory die is electrically connected to the memory package substrate. The silicon capacitor die is disposed on and electrically connected to the second surface of the base.