Standard CMOS Integrated Ultra-Compact Micromechanical Oscillating Active Pixel Arrays

This work demonstrates an ultra-compact low power oscillating micromechanical active pixel array based on a 0.35 μm back-end of line (BEOL)-embedded CMOS-MEMS technology. Each pixel consists of a 3-MHz clamped-clamped beam (CCB) MEMS resonator and a power scalable transimpedance amplifier (TIA) that occupies a small area of 70 × 60 μm
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and draws only 85 μW/pixel. The MEMS resonator is placed next to the TIA with less than 10 μm spacing thanks to the well-defined etch stops in the titanium nitride composite (TiN-C) CMOS-MEMS platform. A multiplexing phase-locked loop (PLL)-driven oscillator is employed to demonstrate the chip functionality. In particular, a nonlinear operation of the resonator tank is used to optimize the phase noise (PN) performance and Allan deviation (ADEV) behavior. The ADEV of 420 ppb averaged over best 3-pixels is exhibited based on such a nonlinear vibration operation.