Low-power, low phase noise (PN) cryogenic frequency generation is required for the control electronics of quantum computers. To avoid limiting the performance of quantum bits, the frequency noise of a PLL should be < 1.9 kHz rms [1]. However, it is challenging for RF oscillators, as the heart of frequency synthesizers to satisfy such a requirement at cryogenic temperatures (CT), since 1) white noise in nanoscale CMOS devices is limited by temperature-independent shot noise; 2) the transistor 1/f noise is much higher, resulting in the oscillator PN being dominated by the 30dB/dec region [1].