Efficient Phase and Quadrature Control of a PZT Resonant MEMS Microscanner with Piezoresistive Position Sensor

This work discloses a closed-loop driving architecture for piezoelectric resonant micromirrors with piezoresistive position sensing, applied to a novel mirror design. The circuit topology is based on two digital negative feedback loops to control the mirror actuation phase and oscillation amplitude. The system design is specifically conceived to handle spurious actuator resonances coupling to the embedded position sensor, which otherwise may cause loop instability in conventional feedback-based oscillators. Additionally, the system ensures operation on the peak of the actuator transfer function, maximizing the efficiency and minimizing actuation voltages. Experimental results show how the proposed approach enables start-up oscillation without locking to any spurious resonant mode. For field-of-view up to 60 degrees, the oscillating frequency is stable within 0.1 ppm and the amplitude within 0.4%, at voltages <30 V.