A rotary-traveling-wave-oscillator-based all-digital PLL with a 32-phase embedded phase-to-digital converter in 65nm CMOS

In this work, we demonstrate a low-phase-noise 4GHz ADPLL with an embedded phase-to-digital converter (PDC), where the rotary traveling-wave oscillator (RTWO) is used as a digitally controlled oscillator (DCO). By using 32 multi phase signals available from the RTWO, the analog phase information is naturally converted into the digital domain, which simplifies the ADPLL architecture while maintaining excellent phase noise both close-in and far-out.