Half bridge topology 500 V pulser for ultrasonic transducer excitation

• Application of half bridge topology for ultrasonic transducer excitation.
• Pulser can generate long pulse trains up to 624 Vp–p.
• Lower frequencies are 1 kHz.
• Upper frequencies are 6 MHz @ 3000 pF load and 10 MHz @ 50 Ω.
• Intrinsic pulser losses are minimised: less than 50 μJ energy per pulse when unloaded.

Application of half bridge topology for ultrasonic transducer excitation using long pulse trains is presented. The novelty of the approach is the high speed solution for a high side drive. A commercially available high speed digital isolator and a high speed MOSFET driver were combined to give the possibility to deliver fast driving signals to a high side N-channel MOSFET. The experimental investigation indicates that the output amplitude of the fundamental harmonic can reach 624 Vp–p for light loads and 552 Vp–p when driving 50 Ω loads. The operation frequency at such voltages can reach 10 MHz for unloaded or 50 Ω load condition and 6 MHz when driving capacitive 3000 pF loads. The output impedance is 13 Ω for voltages below 500 Vp–p and 16–26 Ω for voltages 500 Vp–p and above.