A 28-GHz 189.2-dBc/Hz FoM 360° Phase-Shifting Quadrature Oscillator Without Phase Ambiguity Achieving 0.13° RMS Phase Error Under 2° Phase Resolution

Advanced communication systems, including 5G NR mm-wave applications, have increasing requirements for multiphase low phase noise local oscillators (LOs) to support the complex modulation with image rejection. Meanwhile, for massive MIMO/phased array systems, the LO phase-shifting scheme guarantees the resolution and gain independence of the beam steering with reduced system-level cost and complexity. However, the beam-forming quality of the signal is still limited by the amplitude-phase characteristics of LO phase shifter. Therefore, multi phase oscillator with integrated phase-shifting function is attractive for high-performance array system. Traditional methods for quadrature LO generation include frequency division, polyphase filters, and ring oscillators. However, each of these methods has considerable tradeoffs among the key performances. The ring-type multi phase oscillator based on LC resonator offers low phase noise in the mm-wave domain [1]. However, this method has the issue of phase-mode ambiguity, making it unsuitable for strict phase sequence requirements. The coupled three-stage ring oscillator in [2] generates a 6-phase signal with a phase shift in the single-GHz band. However, the 120° fixed phase difference in such a scheme makes it suffer the severe deterioration of phase noise. The in-phase injection coupled quadrature oscillator [3] deals with the issue of phase noise deterioration with fixed phase, which still meets phase-mode ambiguity.