A Compact Integrated High-Voltage Pulser Insensitive to Supply Transients for 3-D Miniature Ultrasound Probes

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Abstract

In this letter, a compact high-voltage (HV)
transmit circuit for dense 2-D transducer arrays used in 3-D ultrasonic imaging
systems is presented. Stringent area requirements are addressed by a unipolar
pulser with embedded transmit/receive switch. Combined with a capacitive HV
level shifter, it forms the ultrasonic HV transmit circuit with the lowest
reported HV transistor count and area without any static power consumption. The
balanced latched-based level shifter implementation makes the design
insensitive to transients on the HV supply caused by pulsing, facilitating
application in probes with limited local supply decoupling, such as imaging
catheters. Favorable scaling through resource sharing benefits massively
arrayed architectures while preserving full individual functionality. A
prototype of 8 × 9 elements was fabricated in the TSMC 0.18 μm HV BCD
technology and a 160μm×160μm PZT transducer matrix is manufactured on the chip.
The system is designed to drive 65-V peak-to-peak pulses on 2-pF transducer
capacitance and hardware sharing of six elements allows for an area of only
0.008 mm2 per element. Electrical characterization as well as acoustic results
obtained with the 6-MHz central frequency transducer are demonstrated.