Multi-channel drive system of phased array based on DDS chips

Abstract

Ultrasonic phased array focusing transducer has the advantages of adjustable focusing and achieving transcranial focusing. A multi-channel high-precision phase control drive system is one of the key technologies that determine whether it can be used in clinical practice. This paper proposes a design scheme of a phased array drive system based on direct digital synthesizer (DDS) chips. The scheme not only realizes the high-precision phase-controlled output of sine wave and square wave but also in the technical implementation, one electronic channel can be increased with only one main controller general-purpose input/output (GPIO) consumed. This means that the expansion of the number of channels much easier, solving the problem of complicated control circuit caused by the array with dense elements and large aperture. Based on the proposed scheme, a 49-channel array drive system with a phase resolution of 12-bit was fabricated using a microcontroller unit (MCU) as the main control chip. The circuit board test and ultrasonic focusing experiment results show that the phase control error of the multi-channel signal generation board is less than 0.2 degree. And the results of acoustic field distribution obtained by experimental measurement are very similar to those obtained by theoretical simulation, which indicates that the frequency and phase of the output waveform of the array drive system are stable. The design method can provide a reference value for the design of the drive system of phased array transducer with different numbers of elements.