The transmission controller of the animal B-ultrasound system is completed by FPGA, which drives the chip with high-speed MOSFET to transmit ultrasonic signals. The high-speed array switch is used to select the sub array in the probe. In the actual circuit design of animal B-ultrasound, it includes high-voltage pulse modulation circuit and high-speed array selection switch circuit.

In the design process of high-voltage pulse modulation, the following important parameters are mainly considered.

The excitation pulse amplitude of the transducer in the animal B-ultrasound system: The parameter refers to the maximum amplitude of the signal loaded onto the transducer chip, which determines the intensity of the ultrasonic energy emitted by the transducer. At the same frequency, the higher the amplitude, the stronger the energy of the emitted ultrasonic waves. The amplitude of the excitation pulse of the transducer is determined by the external excitation power supply and driver.

Driver response time: In probe driving circuits, MOSFETs are commonly used for driving, including push-pull driving and H-bridge driving. The response time of MOSFET drivers used in this system directly determines the quality of ultrasonic signals. For ultrasonic waves with transmission frequencies between 1MHZ-15MHz, the rise time and fall time of MOSFETs should be selected within 15ns.

Driving capability: The driving capability of MOSFET is also the key to choosing MOSFET, including the highest driving voltage and driving current. As a digital veterinary ultrasound transmission system, the p-MOS driving voltage is not less than -100V, the p-MOS driving voltage is not less than -100V, and the driving current is not less than 2A.

Transmission frequency: The transmission frequency is mainly determined by the transmission controller and matching network. When the transmission frequency is equivalent to the center frequency of the chip, the matching network resonates to produce the maximum transmission power. Of course, as a detection requirement, different transmission frequencies have better detection effects on different detection objects. When using a broadband veterinary ultrasound probe, frequency conversion technology is used to achieve the best detection of ultrasound.