This paper presents the first voltage controlled MEMS oscillator (VCMO) based on the heterogeneous integration of a high Q Lithium Niobate (LN) micromechanical resonator and CMOS. A LN resonator array with a series resonance of 171.1 MHz, a Q of 410, and an electromechanically coupling factor of 12.7% is adopted, while TSMC 65 nm RF LP CMOS technology is used to implement the feedback and tuning circuit with an active area of 220× 70 μ m2. The frequency tuning is achieved by programming a binary weighted digital capacitor bank and a varactor that are both connected in series to the resonator. The oscilla-tor's best measured phase noise performance is -72 and -153 dBc/Hz at 1 kHz and 10 MHz offsets from 178.23 and 175.83 MHz carriers respectively. The VCMO consumes a maximum current of 60 μ A from a 1.2 V supply while realizing a tuning range of 2.4 MHz (∼ 1.4% tuning range). Such VCMOs can be applied to enable ultra-low power, low phase noise, and wideband RF signal synthesis for Internet of Things.