Monolthic Integration of a Filter for Switching Driving Motion in Piezoeletric MEMS Microspeaker

This study presents a novel piezoelectric MEMS microspeaker consisted of cantilever membranes and low-pass filter to enhance bandwidth (Fig. 1). Features of the design: (1) monolithic integration with microspeaker and low-pass filter: to reduce the power consumption and to eliminate SPL zeros wlo external circuits, (2) the low-pass filter supports the gain-modulation driving method. Moreover, the design also easily modulates the 1 st and 2<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> resonances by shifting the cantilever anchors under the same area. Thus, large dynamic responses are achieved from the cantilevers to maintain SPL performance and further expanded the bandwidth by using a low-pass filter. Measurements show the design has full-range (2.7kHz~17kHz) 75dB bandwidth under 0.707V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</inf>+6VDC driving voltage in standard ear simulator (Table 1).