A three-stage differential ring oscillator circuit has a first differential stage, a second differential stage, and a third differential stage and generates six phases (two in each stage) used to form differential in-phase and quadrature-phase clock signals. A cross coupled inverter pair couples the first stage output signals. A second cross coupled inverter pair couples the second stage output signals. A third cross coupled inverter pair couples the third stage output signals. A first interpolator generates a first quadrature-phase clock signal using two phases (one from the positive portion of the second stage and one from the negative portion of the third stage) and a second interpolator generates a second quadrature-phase clock signal using two phases (one from the negative portion of the second stage and one from the positive portion of the third stage). Two phases from the first differential stage form the differential pair of in-phase clock signals.

An injection locked ring oscillator (ILRO) system is disclosed. The ILRO system includes an ILRO circuit configured to receive a plurality of injection control signals and a phase control signal, and to generate a plurality of output clock signals; a phase detector circuit configured to receive the output clock signals and to generate a phase output signal based on phase differences of particular pairs of the output clock signals; and a phase to voltage circuit configured to receive the phase output signal from the phase detector circuit, and to generate the phase control signal based on the phase output signal, where the phase control signal presents a negative feedback phase signal to the ILRO circuit for the phase differences in the particular pairs of the output clock signals.