Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems

Area of Science:

• Medical Imaging
• Electrical Engineering
• Acoustics

Background:

• High frequency ultrasound imaging systems require protection for receivers from high voltage (HV) spikes.
• Traditional diode limiters and commercially available options have limitations in performance at high frequencies.

Purpose of the Study:

• To introduce and evaluate a novel bipolar power transistor (BPT) limiter configuration.
• To compare the performance of the BPT limiter against traditional diode limiters and commercial limiters.
• To assess limiter performance based on insertion loss (IL), total harmonic distortion (THD), and response time (RT).

Main Methods:

• A new bipolar power transistor (BPT) limiter was designed and fabricated.
• The BPT limiter's performance was evaluated for IL, THD, and RT at 100 MHz.
• A comparative analysis was conducted against a diode limiter and a commercial limiter.
• A two-way pulse-echo test was performed using a 100 MHz single element transducer connected to each limiter.

Main Results:

• The BPT-based limiter demonstrated lower insertion loss (-7.7 dB), total harmonic distortion (-74.6 dB), and a faster response time (43 ns) at 100 MHz compared to the commercial limiter.
• Transducer evaluation showed the BPT-based limiter improved -6 dB bandwidth by 22% and sensitivity by 140% over the commercial limiter.
• The BPT limiter effectively minimized signal attenuation, response time, and total harmonic distortion at high frequencies.

Conclusions:

• The BPT-based limiter is a high-performance solution for high frequency ultrasound imaging systems.
• It offers significant advantages over commercial limiters in terms of signal integrity and speed.
• The BPT limiter's design is well-suited for demanding high frequency ultrasound applications.