Abstract: A system and method are provided for combined generation of I and Q signal references according to a periodic input signal and selective phase interpolation of an output signal with reference thereto. A ring oscillator portion generates an oscillator signal, and includes a plurality of delay stages interconnected in cascade to collectively execute an odd number of signal state inversions within a closed loop. The delay stages establish at respective nodes defined therebetween correspondingly delayed oscillator signal versions, successively shifted in phase by a predetermined phase difference. A signal injection portion selectively applies to at least one node of the ring oscillator portion a current bias according to the periodic input signal, and selectively adjusts each current bias in amplitude. The oscillator signal is thereby frequency locked to the periodic input signal, defining I/Q references with respect to the delayed oscillator signal version established at the current biased node.