Design of compact and high-efficiency power supply and power amplifier for parametric array transducer

Parametric array transducers are used for highly directional speaker in an air environments. The power amplifiers for them should have sufficient linear output characteristic to amplify high-frequency ultrasonic waves with low THD, and also have high efficiency to avoid system heating and fuel problems. Piezoelectric micromachined ultrasonic transducers for parametric array transducers need DC-biased voltage driving signals in order to get high-directional quality-sound features. The existing power amplifier such as class A amplifiers has low efficiency and require large volume heatsinks. To overcome the above-mentioned disadvantages of the conventional amplifier, this paper proposes a new power amplifier and also its power supply. The proposed power amplifier system ensures high linearity of output characteristic by utilizing the push-pull class B type amplifier, and furthermore gets high efficiency by providing the DC-DC converter-type power supply of energy recovery feature as well as applying the peak envelope tracking technique. Also the paper suggests the detailed circuit topology. Its characteristics are verified by the detailed experimental results.