Micromechanical Resonator Oscillator

A 10-MHz series resonant micromechanical resonator oscil-lator has been demonstrated using a custom-designed, single-stage, zero-phase-shift sustaining amplifier together with a clamped-clamped beam micromechanical resonator, designed with a relatively large width of 40 µm to achieve substantially lower series motional resistance R x and higher power handling than previous such devices. Using automatic level control (ALC) circuitry to remove an unexpected 1/f 3 close-to-carrier phase noise component, this oscillator achieves a phase noise density of −95 dBc/Hz at 1 kHz offset from the carrier, while consuming only 820 µW of power.