Design and analysis of an electromechanical filter with piezoelectric transducers

Filtering analog signals is certainly not a new topic. It is essential in a variety of applications ranging from communication systems, such as radio, telephone and paging devices, to navigation equipment and system control. It is a subject matter that is more familiar when using strictly electrical components. However, it is known that electromechanical systems, specifically mechanical filters, can also be used to filter signals. Existing mechanical filter technology could be considered to be macro-scale, which encompasses dimensions of centimeters and larger. There is interest in developing micro-scale filters that are well-integrated with electronics. Filter design literature is also quite spread out, making for a design process that is neither precise, nor easily grasped. The objective is to investigate and build a more structured design procedure for developing mechanical filters. This paper presents a design procedure for a mechanical filter. The procedure is carried out, resulting in a three-resonator piezoelectric filter (with 1500 Hz center frequency) that is built and tested. The results are presented, indicating how closely the design specifications are met. The desire is to use this general process to design and fabricate a micro-scaled device in the future.