Patent ID: 7656239

Claim:
A multi-phase oscillator including a plurality of resonator stages series-connected in an ordered closed loop each one for providing at least one oscillating voltage corresponding to an oscillating current including a natural current being generated by the stage and at least one injected current from a previous stage in the closed loop, the oscillating voltages provided by all the stages having substantially the same frequency, and the at least one oscillating voltage provided by each stage and the at least one previous oscillating voltage provided by the previous stage having a corresponding phase difference, wherein the oscillator further includes a coupler between each stage and the previous stage for generating the at least one injected current according to the at least one previous oscillating voltage, the coupler including transconductance means having a current source for transforming at least one voltage corresponding to the at least one previous oscillating voltage into at least one current corresponding to the at least one injected current, and shifting means for shifting the phase of the at least one injected current according to the corresponding phase difference; wherein the shifting means includes filtering means for filtering the at least one previous oscillating voltage into at least one corresponding filtered oscillating voltage to be supplied to the transconductance means; wherein the filtering means includes at least one RC filter.