In this paper, a compact, low-loss, dual-path phaseswitched inductor suitable for millimeter-wave (mmWave) transceiver subblocks is proposed. The signal path through the structure is determined by the relative polarity of two differential excitation signals applied to the four-port structure. Because inductance is varied by altering signal path through the inductor, signal-path MOSFET switches are avoided. The inductor, therefore, demonstrates high, mode-invariant quality factor, facilitating the design of high-performance dual-band mmWave transceiver subblocks. Based on the proposed inductor, a dualband Ka-band oscillator is designed in a 65-nm CMOS technology which covers two frequency bands from 14.8 to 18.7 GHz and from 20.8 to 26.6 GHz. The proposed inductor facilitates a widely tunable, dual-band frequency range while maintaining the state-of-the-art phase noise, power consumption, and figure of merit (FoM). The oscillator achieves measured fractional tuning ranges of 23.3% and 24.5% and phase noise of -115.1 dBc/Hz at 2-MHz offset while consuming only 4.8-mW dc power. A peak tuning-range FoM of -195.1 and -194.9 dBc/Hz is demonstrated across the low-and high-frequency bands.
