High-precision Driving System Research Of Ultrasound Phased Array

Phased High Intensity Focused Ultrasound (HIFU) can help to achieve flexible, controllable synthesized ultrasound beam by exciting each element of an ultrasonic array transducer with independent phase delay. Using the ultrasound peculiar capability of penetration, orientation and focusing, phased HIFU can build high intensity focus in deep tissue and cause acute cell death with high temperature.It is a hotspot of therapeutic ultrasound and Tumor thermotherapy fields.High precision ultrasonic transmission phased delay is the key technology in phased array ultrasonic beams. The basic link to achieve ultrasound phased array is phase delay. To achieve dynamic focus, deflection, beam forming, and other phased results need precise control of phase delay. Theoretical analysis showed that only to improve the precision, resolution and stability of phase delay. it can significantly inhibit sidelobe.This paper mainly developed driving system of phased HIFU system from the phase delay. The main contents are as follows:1. The principles and its implementation of digital waveform phase delay based on waveform excitation is explained, and it also analysed the method and significance of promoting phase precision.2. Designed high-precision ultrasonic delay circuit, based on FPGA technique, a 64-channel phased-signal driving system is developed, which could provide 8-bit phase control in a range of frequency where the frequency is 1 MHz, and the function of accurate phase shift for multiplex signals is implemented. It can satisfy the need of high precision ultrasonic delay.3. Based on DDS(Direct Digital Synthesis)technique, combined with ultrasonic phased array, a new signal driving system is researched by improving DDS frame, through four-way simulation, we know that the control precision can meet the need. Besides, this paper has also carried on the discussion and research to periphery control circuit.Experimentation has proved that the driving system by this paper can reduce the additional phase difference between channels, improve system stability and achieve the precision need.