Novel power MOSFET-based expander for high frequency ultrasound systems

Abstract

The function of an expander is to obstruct the noise signal transmitted by the pulser so that it does not pass into the transducer or receive electronics, where it can produce undesirable ring-down in an ultrasound imaging application. The most common type is a diode-based expander, which is essentially a simple diode-pair, is widely used in pulse-echo measurements and imaging applications because of its simple architecture. However, diode-based expanders may degrade the performance of ultrasonic transducers and electronic components on the receiving and transmitting sides of the ultrasound systems, respectively. Since they are non-linear devices, they cause excessive signal attenuation and noise at higher frequencies and voltages. In this paper, a new type of expander that utilizes power MOSFET components, which we call a power MOSFET-based expander, is introduced and evaluated for use in high frequency ultrasound imaging systems. The performance of a power MOSFET-based expander was evaluated relative to a diode-based expander by comparing the noise figure (NF), insertion loss (IL), total harmonic distortion (THD), response time (RT), electrical impedance (EI) and dynamic power consumption (DPC). The results showed that the power MOSFET-based expander provided better NF (0.76 dB), IL (-0.3 dB) and THD (-62.9 dB), and faster RT (82 ns) than did the diode-based expander (NF (2.6 dB), IL (-1.4 dB), THD (-56.0 dB) and RT (119 ns)) at 70 MHz. The -6 dB bandwidth and the peak-to-peak voltage of the echo signal received by the transducer using the power MOSFET-based expander improved by 17.4 % and 240 % compared to the diode-based expander, respectively. The new power MOSFET-based expander was shown to yield lower NF, IL and THD, faster RT and lower ring down than the diode-based expander at the expense of higher dynamic power consumption.

High-efficiency high-voltage class F amplifier for high-frequency wireless ultrasound systems

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A high-power ultrasonic pulser-receiver for concrete non- destructive testing

“…Insulated Gate Bipolar Transistor(IGBT) is a kind of power device that consists of Bipolar Junction Transistor(BJT) and MOS transistor. It is selected as the power switch due to its advantage of low driven power, low saturation voltage and fast switching speed [4][5] . In this design, the module of 1HW25N120R2 IGBT was applied, which could support the maximum current of 30A and the permissible voltage of 300V.…”

Power Amplifier Linearizer for High Frequency Medical Ultrasound Applications

“…Designing linear PAs to operate at high frequencies is very challenging since the parasitic impedances of their electronic components become more dominant at higher frequencies [1,2]. Furthermore, the simulation model of the power MOSFET device, which is the main component of a PA, is inaccurate for high-voltage operation [3-5]. …”