A reference signal generator includes an integrated circuit substrate having a semiconductor resonator therein. The resonator includes an inductor extending adjacent a first surface of the integrated circuit substrate. A vertically-stacked composite of at least first and second electrically insulating dielectric layers is provided on the integrated circuit substrate. The vertically-stacked composite covers a portion of the first surface, which extends opposite the inductor. A first electrically conductive shielding layer is provided on a portion of the second electrically insulating dielectric layer extending opposite the inductor. The first electrically conductive shielding layer may encapsulate exposed portions of the first and second electrically insulating dielectric layers. The shielding layer may operate as an electromagnetic shield between the inductor and an external structure, such as an integrated circuit package, and also shield against environmental contamination (e.g., external moisture penetration).