Supply-Doubled Pulse-Shaping High Voltage Pulser for CMUT Arrays

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Materials Science

Background:

• Medical ultrasound imaging relies on efficient pulse generation for high-resolution imaging.
• Capacitive micromachined ultrasonic transducers (CMUTs) require specialized high voltage (HV) pulsers for optimal performance.
• Conventional pulsers face limitations in output voltage and signal shaping capabilities.

Purpose of the Study:

• To develop a supply-doubled HV pulser for medical ultrasound applications, specifically for CMUTs.
• To overcome the supply voltage limitations of existing unipolar pulsers.
• To enable generation of three-level pulses for improved transmit pressure signal optimization.

Main Methods:

• Implementation of a bootstrap circuit combined with dynamically-biased stacked transistors for HV operation.
• Design and fabrication of a proof-of-concept prototype using 0.18-μm HV CMOS/DMOS technology.
• Testing with a 2 pF, 8.3 MHz CMUT, adjusting pulse shape for maximum pressure output.

Main Results:

• The HV pulser safely generates controllable three-level pulses up to 85 Vpp from a 45 V supply, exceeding the supply voltage limit.
• Achieved output signals nearly twice the supply level, overcoming conventional pulser limitations.
• Acoustic measurements demonstrated good agreement with large signal CMUT models, confirming effective pulse shaping for maximum pressure.

Conclusions:

• The developed supply-doubled HV pulser effectively enhances CMUT performance in medical ultrasound imaging.
• The novel design offers a reliable solution for achieving higher output voltages and advanced pulse shaping.
• This technology holds significant potential for advancing ultrasound imaging capabilities and diagnostic accuracy.