Design and Characterization of a Frequency- and Amplitude-Controlled CMOS MEMS Resonant Scanning Mirror

This letter presents a micromachined, electromagnetically driven scanning mirror that uses complementary metal-oxide-semiconductor (CMOS) technology and has the potential for use in light detection and ranging (LiDAR) systems. The device has an integrated drive coil and an angle sensor, which are conveniently constructed using metal layers and an n-type silicon piezoresistor, respectively. The fabricated device showed a measured resonance frequency of 1266 Hz with a quality factor of 109. The design demonstrated excellent drive efficiency, producing an optical angle of 32.6° at a drive current of 4.8 mA
_pp
. Furthermore, a closed-loop control system for the scanning amplitude and frequency was implemented, which utilized the demodulated amplitude and phase of the piezoresistive sensing signal. The amplitude control achieved a settling time on the order of tens of milliseconds and a long-term variation of only 1.512 ppb/min. This is a significant improvement over the uncontrolled value of −43.7 ppm/min. Overall, the results of this study demonstrate the potential of the CMOS micromachined electromagnetically driven scanning mirror as a promising component for LiDAR systems.