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A rotary traveling-wave oscillator (RTWO) has an ability to generate multiple phases at millimeter-wave (mmW) frequencies while achieving low phase noise (PN). Unfortunately, due to the practically unavoidable transmission line (TL) dispersion, which causes the higher-order harmonics to travel faster than the fundamental, RTWOs suffer from flicker noise upconversion. In this article, we propose a "distributed stubs" technique to mitigate this mechanism in which tuning capacitors placed on the TL stubs away from the maintaining amplifiers will slow down the travel speed of higher-order harmonics relative to the fundamental, thus lowering the phase shifts due to the TL dispersion. We further provide a comprehensive analysis of the flicker noise upconversion mechanism due to the TL dispersion. The proposed 26.2-30-GHz RTWO is implemented in 22-nm fully depleted silicon-on-insulator (FD-SOI) CMOS with eight differential phases. At 30 GHz, it achieves PN of −107.6 and −128.9 dBc/Hz at 1-and 10-MHz offsets, respectively. This translates into figures-of-merit (FoMs) of 184.2 and 185.4 dB, respectively, for a single phase. The proposed architecture consumes 20 mW from 0.8-V supply. It achieves a flicker PN corner of 180 kHz, which is an orderof-magnitude better than currently achievable by state-of-the-art mmW RTWOs.

In this letter, we propose a 32-42 GHz frequency quadrupler that performs digital logic operations between four phase-shifted differential signals at one-fourth of the output frequency. The four phase-shifted signals are generated via a 10 GHz rotary traveling-wave oscillator (RTWO) and are symmetrically routed to the quadrupler using a CMOS buffered clock tree. The harmonic rejection ratio (HRR) is enhanced by employing a differential LC filter tuned at its output center frequency. The proposed frequency quadrupler is implemented in 22-nm FD-SOI CMOS. At 37 GHz, it produces an output power of −4 dBm with a 10% drain efficiency. It consumes 4 mW from 0.8 V supply and occupies a core area of 0.021 mm 2 . The worstcase HRR for fundamental. second, third, and fifth harmonics are 41.3, 48.6, 41.3, and 37.3 dBc, respectively.

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