Integrated analog beam former based on bucket brigade device for micromachined ultrasonic sensor array

Abstract

Micromachined ultrasonic sensors are promising in the applications including medical imaging, non-destructive evaluation (NDE), ranging, and object detections. Bucket brigade device (BBD) was used as the analog beam former for piezoelectric micromachined ultrasonic sensor phased array. The works on the optimization of BBD, including improvement of the transfer efficiency and dynamic range, and simplification of system design were discussed in details. The parasitic insensitive approach was proposed to optimize the properties of BBD delay line, and measured results indicated that this approach achieved larger charge transfer efficiency, larger dynamic range, and higher frequency than the conventional BBD. Furthermore, the BBD distributed delay-sum architecture was proposed to reduce chip area, simplify system design, and achieve monolithic integration. The measured results indicated that BBD distributed delay-sum architecture showed the beam forming property that is consistent to the theoretical calculation very well.