Abstract
This study demonstrates a novel piezoelectric micro-electromechanical system (MEMS) microspeaker with wide bandwidth at high range for in-ear applications. The microspeaker is composed of eight high-frequency range triangular cantilevers anchored on a square frame. Merits of the design to modulate resonant frequencies of cantilevers are, (1) domain variation: change the dimensions of cantilevers inside the supporting frame, (2) boundary variation: change the boundaries of cantilevers outside the support frame. Thus, multiple sound pressure level (SPL) poles and wide bandwidth are achieved. Measurements in the standard ear simulator (driven at 0.707Vrms input signal with out-of-phase driving method) demonstrate the proposed design increases the bandwidth to 3.7∼14.0kHz when SPL is 90dB, as summarized in Table 1.