Novel ultrasonic dynamic focusing system with reduced hardware complexity

Dynamic focusing is known to be the best way to improve image resolution, but it needs very complex and bulky hardware for an array transducer with a large number of elements, such as a sector phased array with 128 elements or a two-dimensional array with more elements. We describe an efficient architecture for ultrasonic dynamic focusing using both analog and digital processing techniques to minimize the hardware complexity. This new focusing hardware consists of a specially designed Analog First-In-First-Out (AFIFO) device, one for each element, a Sampling Clock Generator (SCG), and a simple multi-input analog adder for a whole system. The SCG generates nonuniform sampling clocks to adjust the sampling instances of the input pulse echo of each AFIFO corresponding to the propagation times between the array element and each imaging point. The AFIFO stores and outputs analog values of these samples on a First-In First-out basis. Finally, the outputs of AFIFO's are summed together by the analog adder. We will discuss the hardware reduction ratio of the proposed architecture compared with conventional ones. Preliminary experimental results will also be presented.