A Doherty Power Amplifier for Ultrasound Instrumentation

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Acoustics

Background:

• Linear power amplifiers in ultrasound systems exhibit low power efficiency, leading to heat generation and degraded echo signal quality.
• Existing Doherty power amplifier designs, while efficient in communication systems, require adaptation for ultrasound applications due to signal distortion concerns.

Purpose of the Study:

• To develop a novel power amplifier scheme for ultrasound instrumentation that enhances power efficiency.
• To maintain or improve the echo signal quality of measured targets using the new amplifier design.

Main Methods:

• A Doherty power amplifier was specifically re-designed for ultrasound instrumentation.
• The amplifier's performance was characterized by measuring gain, output 1-dB compression point, and power-added efficiency at 25 MHz.
• The amplifier's functionality was validated through pulse-echo response tests with an ultrasound transducer.

Main Results:

• The designed Doherty power amplifier achieved a gain of 33.71 dB, an output 1-dB compression point of 35.71 dBm, and a power-added efficiency of 57.24% at 25 MHz.
• Pulse-echo tests demonstrated a comparable echo signal amplitude (0.9698 V peak-to-peak) when using the amplifier with a focused ultrasound transducer.
• The amplifier successfully delivered 43.06 dBm output power at 25 MHz for pulse-echo measurements.

Conclusions:

• The re-designed Doherty power amplifier effectively improves power efficiency in ultrasound instrumentation.
• The developed amplifier maintains adequate echo signal quality, making it suitable for medical ultrasound applications.
• This advancement offers a more efficient solution for ultrasound power amplification, potentially reducing heat generation and improving device performance.