An imaging system may include an image sensor die stacked on top of a digital signal processor (DSP) die. Through-oxide vias (TOVs) may be formed in the image sensor die and may extend at least partially into in the DSP die to facilitate communications between the image sensor die and the DSP die. The image sensor die may include light shielding structures for preventing reference photodiodes in the image sensor die from receiving light and in-pixel grid structures for preventing cross-talk between adjacent pixels. The light shielding structure may receive a desired biasing voltage through a corresponding TOV, an integral plug structure, and/or a connection that makes contact directly with a polysilicon gate. The in-pixel grid may have a peripheral contact that receives the desired biasing voltage through a light shield, a conductive strap, a TOV, and/or an aluminum pad.