FPGA-based underwater ultrasonic phased transmitting system using CMUTs

In order to enhance the characteristics of underwater ultrasonic imaging system with small volume, low power supply voltage and easy integration, the underwater ultrasonic phased transmitting system is designed. Using field programmable gate array (FPGA) to control the excitation signals time-delay of 16 channels to achieve phased transmitting, and capacitive micro-machined ultrasonic transducer arrays (CMUTs) as the transmitting transducer. Then the operational amplifier and power amplifier circuit are designed and can be effectively improved the amplitude and power of the transmitting signals. The experimental results show that, the system can generate the excitation pulse signals with high frequency and high voltage, achieve phase time-delay precision to the minimum of 2.5ns, and echo signals of the imaging experiments are clearly. It provides a hardware foundation for the research of underwater ultrasonic imaging system.