A Novel Bipolar Pulse Generator for High-frequency Ultrasound System

Pulse generator is the critical component in all ultrasound systems for driving a piezoelectric transducer to medical or nondestructive testing (NDT) applications. The transducer in ultrasound system was driven by a pulse train generator, which delivers high-voltage bipolar or unipolar pulse train. Several recent papers have discussed both the importance and the design of unipolar and bipolar pulse generator for ultrasound applications. Bipolar voltage pulse has lower unwanted DC and low-frequency component could decrease the leakage current. Also, its peak-to-peak pulse voltage could achieve twice of the voltage rating of the coaxial cable connecting the generator and the transducer. In current commercial ultrasound systems, bipolar pulse generators are commonly used; however, it still had some disadvantages like longer pulse length, which limited the driving frequency and affect the signal performance. This paper purposed a novel design of bipolar pulse generator based on a novel dual P-N channel MOSFET and FPGA timing control. It could produce multi-cycle pulses with center frequency over 50 MHz and shorter pulse length. This design also preserved the low-cost advantage compared to other commercial design of bipolar pulse generator. It is suitable for high-frequency ultrasound Doppler and B-mode imaging applications.