A Class-J Power Amplifier Implementation for Ultrasound Device Applications.

Kiheum You,Hojong Choi,Seung-Hwan Kim

doi:10.3390/s20082273

Kiheum You, Hojong Choi + Show 1 more

Open Access

https://doi.org/10.3390/s20082273

Copy DOI

Abstract

In ultrasonic systems, power amplifiers are one of the most important electronic components used to supply output voltages to ultrasonic devices. If ultrasonic devices have low sensitivity and limited maximum allowable voltages, it can be quite challenging to detect the echo signal in the ultrasonic system itself. Therefore, the class-J power amplifier, which can generate high output power with high efficiency, is proposed for such ultrasonic device applications. The class-J power amplifier developed has a power efficiency of 63.91% and a gain of 28.16 dB at 25 MHz and 13.52 dBm input. The pulse-echo measurement method was used to verify the performance of the electronic components used in the ultrasonic system. The echo signal appearing with the discharged high voltage signal was measured. The amplitude of the first echo signal in the measured echo signal spectrum was 4.4 V and the total-harmonic-distortion (THD), including the fundamental signal and the second harmonic, was 22.35%. The amplitude of the second echo signal was 1.08 V, and the THD, including the fundamental signal and the second harmonic, was 12.45%. These results confirm that a class-J power amplifier can supply a very high output echo signal to an ultrasonic device.

Highlights

Ultrasound is a sound wave with a frequency of 16 kHz or higher, a frequency range above the hearing threshold of humans [1]
Class-J power amplifiers have been used in RF or telecommunication systems due to the advantages of their high power with high efficiency
Miniaturized ultrasonic transducers require high power with limited maximum allowable voltages, a class-J power amplifier with external matching circuit was designed to be used for such ultrasonic devices with low sensitivities

Summary

Introduction

Ultrasound is a sound wave with a frequency of 16 kHz or higher, a frequency range above the hearing threshold of humans [1]. Ultrasound technology is used in a variety of fields, such as cleaning or fingerprint recognition in a living room, parking assistance devices in autonomous vehicles using ultrasonic distance measurement, and image-based diagnosis of muscles, tendons, and internal organs [2,3,4,5]. It is used for the nondestructive testing and measuring of material defects and the thickness of objects [6]. The reflected ultrasonic signal of such an ultrasound device is so small that a signal with an appropriate power amplifier output is required for accurate detection [6]

Methods

Results

Conclusion