CMOS micromechanical resonator oscillator

A completely monolithic high-Q oscillator, fabricated via a combined CMOS plus surface micromachining technology, is described, for which the oscillation frequency is controlled by a polysilicon micromechanical resonator to achieve stability and phase noise performance comparable to those of quartz crystal oscillators. It is shown that the closed-loop, steady-state oscillation amplitude of this oscillator can be controlled through the DC-bias voltage applied to the capacitively driven and sensed /spl mu/resonator. Measurements indicate a phase noise density level of -168 dBm/Hz at 5 kHz offset frequency for an oscillator carrier power of -14.5 dBm.<<ETX>>