Abstract
This study demonstrates the piezoelectric MEMS microspeaker based on cantilever-plate actuators, connecting with a central-diaphragm by meandering springs. Moreover, a filter circuit is designed to manage the input signal to change the mode shape, further enhance the bandwidth. Features and merits of the proposed design are: (1) cantilever-plate actuators : applying large displacement on central diaphragm to enhance SPL (Sound-Pressure-Level), (2) meandering connecting springs: releasing residual stresses on springs and transmit displacement to central diaphragm, (3) central diaphragm with driving electrode : offering additional out-of-plane displacement by drum motion of central diaphragm, (4) all-pass filter : processing the input signal of central diaphragm to avoid SPL zero. Measurements under 0.707 Vrms (9 Vdc) driving voltage in standard ear simulator, proposed design reaches two-fold enhancement of bandwidth >75 dB (1 kHz~15.4 kHz) compared to reference design.