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Open AccessArticle

Development of a Class-C Power Amplifier with Diode Expander Architecture for Point-of-Care Ultrasound Systems

Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea
Micromachines 2019, 10(10), 697; https://doi.org/10.3390/mi10100697
Received: 8 September 2019 / Revised: 10 October 2019 / Accepted: 11 October 2019 / Published: 14 October 2019
(This article belongs to the Special Issue Piezoelectric Transducers: Materials, Devices and Applications)
Point-of-care ultrasound systems are widely used in ambulances and emergency rooms. However, the excessive heat generated from ultrasound transmitters has an impact on the implementation of piezoelectric transducer elements and on battery consumption, thereby affecting the system’s sensitivity and resolution. Non-linear power amplifiers, such as class-C amplifiers, could substitute linear power amplifiers, such as class-A amplifiers, which are currently used in point-of-care ultrasound systems. However, class-C power amplifiers generate less output power, resulting in a reduction of system sensitivity. To overcome this issue, we propose a new diode expander architecture dedicated to power amplifiers to reduce the effects of sinusoidal pulses toward the power supply. Thus, the proposed architecture could increase the input pulse amplitudes applied to the main transistors in the power amplifiers, hence increasing the output voltage of such amplifiers. To verify the proposed concept, pulse-echo responses from an ultrasonic transducer were tested with the developed class-C power amplifier using a resistor divider and the designed diode expander architecture. The peak-to-peak amplitude of the echo signals of the ultrasonic transducers when using a class-C power amplifier with a diode expander architecture (2.98 Vp–p) was higher than that for the class-C power amplifier with a resistor divider architecture (2.51 Vp–p). Therefore, the proposed class-C power amplifier with diode expander architecture is a potential candidate for improving the sensitivity performance of piezoelectric transducers for point-of-care ultrasound systems. View Full-Text
Keywords: class-C power amplifier; diode expander; piezoelectric transducers; point-of-care ultrasound systems class-C power amplifier; diode expander; piezoelectric transducers; point-of-care ultrasound systems
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Choi, H. Development of a Class-C Power Amplifier with Diode Expander Architecture for Point-of-Care Ultrasound Systems. Micromachines 2019, 10, 697.

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