Effect of Tapered Angle on BAW Transducer Performance for Ultrasonic Wavefront Computing

Fourier Transform (FT) is one of the most extensively used scientific computations for signal/image processing. Recently, an emerging highly efficient ultrasonic wavefront computing (WFC) technique was developed to compute the Fast Fourier Transform (FFT) physically using bulk acoustic wave (BAW) piezoelectric transducers and a Fresnel lens. Typically, cuboid shapes are used for BAW transducers to model the ultrasonic WFC system. However, the shape of such transducers is usually non-uniformly tapered due to the fabrication process. In this paper, we investigate the effect of different tapered angles on BAW transducers for ultrasonic WFC system using full-wave simulation, in particular, the errors of the WFC computed FFT due to having transducers with tapered angles varying from 0 to 60 degrees. The simulation results show that the average pressure field of a single transducer at the observation plane decreases as the tapered angle increases. In addition, larger errors of the WFC computed FFT results occur when the tapered angles of the transducer array become larger. Therefore, the effect of the tapered angle on BAW transducers should be considered for more accurate ultrasonic WFC computed FFT.