A new technique using a left-handed (LH) resonator to generate a multiband millimeter-wave carrier signal is proposed in this paper. The LH resonator exhibits nonlinear dispersion characteristic, which enables uneven spacing between resonant frequencies. With stages of the LH unit cell, there are resonant frequencies from the nonlinear dispersion curve. Moreover, the band selection switches are not located in the signal path, which can, therefore, dramatically reduce the size of switches and improve the overall quality factor of the resonator. A dual-band millimeter-wave oscillator in digital 90-nm CMOS technology is implemented to demonstrate this new technique. Using a mode selection switch, the proposed oscillator operates at 21.3 and 55.3 GHz, respectively, with a total power consumption of 14 mW.