Abstract: An ultrasonic transducer including a membrane film and a perforated baseplate. The baseplate can have a conductive surface with a plurality of perforations formed through the baseplate. The membrane film can have a conductive surface and be positioned under tension proximate to the perforations formed through the baseplate. The tension of the membrane film can be controlled to provide a restoring force to counteract the moving mass of the membrane film, and the moving mass of air in the perforations of the baseplate. By selecting the diameter(s) of the perforations of the baseplate, the thickness of the baseplate, the thickness of the membrane film, the tension of the membrane film, and/or the bending stiffness of the membrane film, a wide bandpass frequency response of the ultrasonic transducer centered at an ultrasonic frequency of interest can be obtained and tailored to a desired application.

Abstract: An ultrasonic transducer including a membrane film and a perforated baseplate. The baseplate can have a conductive surface with a plurality of perforations formed through the baseplate. The membrane film can have a conductive surface and be positioned under tension proximate to the perforations formed through the baseplate. The tension of the membrane film can be controlled to provide a restoring force to counteract the moving mass of the membrane film, and the moving mass of air in the perforations of the baseplate. By selecting the diameter(s) of the perforations of the baseplate, the thickness of the baseplate, the thickness of the membrane film, the tension of the membrane film, and/or the bending stiffness of the membrane film, a wide bandpass frequency response of the ultrasonic transducer centered at an ultrasonic frequency of interest can be obtained and tailored to a desired application.

Abstract: A device and method for driving a capacitive load that has a more power efficient design. The power efficient capacitive load driving device can be used to drive one or more acoustic transducers of a parametric audio system with low distortion and a flat frequency response. The capacitive load driving device includes a current source, a plurality of switches interconnected in an “H-bridge” configuration coupled to an output of the current source, and a controller. The plurality of interconnected switches is coupleable to at least one capacitive load. By driving the capacitive load with at least one controlled switched drive signal, the capacitive load driving device delivers (recovers) energy to (from) the capacitive load in an optimal manner, thereby generating a desired output voltage waveform across the capacitive load with increased power efficiency.