中文摘要：

设计了一种脉冲宽度调制的H桥超声发射电路，该电路由PWM电路、H桥功率放大电路、低通滤波电路组成。该发射电路具有结构简单、输出功率高、可对大部分的波形进行调制发射、易于多通道拓展的优点。通过时该电路进行仿真和实际电路的测试，证明所产生波形满足设计要求，并可以用于超声探测和成像系统。

英文摘要：

In this paper, a H bridge ultrasonic transmitting circuit with pulse width modulation is designed, which is composed of PWM circuit, H bridge power amplifier circuit and low-pass filter circuit. The circuit has the advantages of simple structure, high output power, and can modulate the majority of the waveform, easy multi-channel expansion. Through the test of the circuit and the actual circuit, it is proved that the waveform meets the design requirements and can be used for ultrasonic detection and imaging system.