A miniaturized phased high intensity focused ultrasound transducer-driven system with MR compatibility

Abstract

A new transducer-driven system is designed for these important characteristics: lower harmonic energy, higher integration and more flexible wave output mode. According to the flowing direction of signals, the whole system mainly has three parts: the controlling module based on FPGA, the wave generator group and the signal processing group. FPGA concurrently controls the following wave generator groups by digital signals outputting in parallel. The wave generator, which could generate continuous sine wave and pulse wave in a low harmonic energy level, has a programmable Direct Digital Synthesizer (DDS) with a 12 bit Digital to Analog Converter (DAC) and sampling up to 180 MSPS. The signal processing group contains the amplification module and the matching network group for transducers. The power of sine wave is magnified by integrated operational amplifier (op amp). The matching network is designed for the transducer with frequency 1.36MHz. Finally the measurement of one channel output shows that: the frequency accuracy is 1.36MHz ±0.04MHz and the wave mode can be configured as continuous sine wave or pulse wave. The amplitude of each harmonics in the FFT analysis is over 50dB lower than the fundamental component. The acoustic power of one circular transducer with radius of 5mm is more than 2.8W.