Systems and methods which provide oscillator configurations implementing phase rotation (rotated-phase-tuning (RPT)) are described. Embodiments of a RPT oscillator may employ phase interpolation, whereby two current vectors having different phases are superimposed to provide a resultant current vector having a tunable phase to vary a phase shift in a feedback loop of an oscillator circuit and correspondingly tune the oscillation frequency. Phase rotation provided by an RPT oscillator configuration of embodiments inserts a negative phase shift (rotation phase shift) into each of two current branches to rotate the phase shifts of a phase-tuning technique, such as for avoiding phase ambiguity with respect to tunable oscillation frequencies. RPT oscillators of embodiments are varactor-less and are particularly well suited for operation to provide output frequencies in the millimeter-wave (mmW) band.