Abstract
This study presents a novel piezoelectric MEMS microspeaker consisted of the cantilever-plate actuator, central-diaphragm, and connecting meandering-springs. Features of the design: (1) cantilever-plate actuator: supply large actuation force with simple electrical routing, (2) central-diaphragm: simple Si layer structure to provide relatively flat piston motion, (3) connecting meandering-spring: transmit actuation force to central-diaphragm and reduce the influence of thin film residual stresses. Thus, large average central-diaphragm out-of-plane displacement is achieved, and the piston mode of microspeaker excited by cantilever-plate actuators could ensure good THD (Total-Harmonic-Distortion i.e. high fidelity) response. Measurements show the design has a maximum SPL (Sound-Pressure-Level) of 123 dB and full-range (20 Hz∼20 kHz) 80dB bandwidth with overall THD below 7 % under 0.707 Vrms+10 VDC driving voltage in standard ear simulator.