A cam phasing system is provided. In some non-limiting examples, the cam phasing system includes a planetary actuator having a first sun gear, a first set of planet gears meshed to and arranged circumferentially around the first sun gear, a first ring gear meshed with the first set of planet gears, and a second sun gear. The second sun gear is rotationally fixed. The planetary actuator further includes a second set of planet gears meshed to and arranged circumferentially around the second sun gear, a second ring gear meshed with the second set of planet gears, and an input shaft rotationally coupled to the first sun gear for rotation therewith. Rotation of the input shaft rotates the first ring gear relative to the second ring gear.