摘要
This study presents a piezoelectric MEMS microspeaker address high-frequency SPL decay, the design adopts a dual-motion strategy: two actuators directly coupled to the diaphragm generate piston motion for low-frequency performance, while two additional independent actuators introduce a high-frequency bending mode to enhance output via out-of-phase driving. The reverse-trapezoidal cantilever-plate actuator with a relatively large movable area is exploited in this study. The key design features consist of employing only two diaphragm-connected actuators to achieve piston motion, maintaining low-frequency performance compared with the four-actuator configuration and incorporating two independent actuators to create a bending mode, thereby improving high-frequency response with out-of-phase driving. Under 0.7Vrms+5Vdc excitation, the proposed design achieves an SPL bandwidth of 160Hz similar to 22.3kHz (> 70dB), outperforming the reference (130Hz similar to 18.3kHz). Furthermore, the design demonstrates improved THD bandwidth of 8.6kHz similar to 16.3kHz (< 6%) under 0.7Vrms, better than the reference (7.7kHz similar to 13.7kHz). Table 1 summarizes the results and corresponding comparisons.