  Very small electromechanical coupling coefficient in micro-electromechanical
systems (MEMS) or acoustic resonators is quite of a concern for oscillator
performance, specially at mmWave frequencies. This small coefficient is the
manifestation of the small ratio of motional capacitance to static capacitance
in the resonators. This work provides a general solution to overcome the
problem of relatively high static capacitance at mmWave frequencies and
presents analysis and design techniques for achieving extremely low phase noise
and a very high figure-of-merit (FoM) in an on-chip MEMS resonator based mmWave
oscillator. The proposed analysis and techniques are validated with design and
simulation of a 30 GHz oscillator with MEMS resonator having quality factor of
10,000 in 14 nm GF technology. Post layout simulation results show that it
achieves a phase noise of -132 dBc/Hz and FoM of 217 dBc/Hz at offset of 1 MHz.
