Phase Error Calibration Technique for Rotary Traveling Wave Oscillators

Phase error calibration technique that is suitable for an RTWO is presented. By introducing non-uniform capacitors in the distributed resonator, the phase relationships among multiphase outputs available from the RTWO are adjusted to compensate for physical asymmetries. To have a better understanding of the proposed method, we develop a model in which the RTWO is described as injection locked multiple SWOs. The proposed model reveals possible modes of oscillation, their stability, and provides better design insight. The prototype is fabricated in a 110 nm RF-CMOS process, demonstrating more than 10° phase control range at the vicinity of 3 GHz oscillation frequency.