A Doherty Power Amplifier for Ultrasound Instrumentation

2023

Sensors

Self Cite

An inverse Class-E power amplifier was designed for an ultrasound transducer. The proposed inverse Class-E power amplifier can be useful because of the low series inductance values used in the output matching network that helps to reduce signal distortions. Therefore, a newly designed Class-E power amplifier can obtain a proper echo signal quality. The measured output voltage, voltage gain, voltage gain difference, and power efficiency were 50.1 V, 22.871 dB, 0.932 dB, and 55.342%, respectively. This low voltage difference and relatively high efficiency could verify the capability of the ultrasound transducer. The pulse-echo response experiment using an ultrasound transducer was performed to verify the capability of the proposed inverse Class-E power amplifier. The obtained echo signal amplitude and pulse width were 6.01 mVp-p and 0.81 μs, respectively. The −6 dB bandwidth and center frequencies of the echo signal were 27.25 and 9.82 MHz, respectively. Consequently, the designed Class-E power amplifier did not significantly alter the performance of the center frequency of the ultrasound transducer; therefore, it could be employed particularly in certain ultrasound applications that require high linearity and reasonable power efficiency.

Section: Resultsmentioning

confidence: 99%

An Inverse Class-E Power Amplifier for Ultrasound Transducer

2023

Sensors

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“…After the careful selection of the transistor, design parameters such as the gain, bandwidth, harmonic distortion, linearity, and efficiency need to be considered. In general, a high-gain power amplifier is desirable because a low-sensitivity ultrasonic transducer requires high-voltage or high-current signals to be triggered [ 101 ]. The power amplifier bandwidth must be higher than that of the transducer [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

Power Amplifier Design for Ultrasound Applications

2023

Micromachines

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A design analysis of the power amplifiers developed for ultrasound applications was conducted because ultrasound applications require different types of power amplifiers, which are one of the most critical electronic components in ultrasound systems. To generate acoustic signals using transducers, which are among the most important mechanical devices in ultrasound systems, an appropriate output voltage, current, or power signal must be produced by a power amplifier. Therefore, an appropriate design analysis of the power amplifier must be conducted to obtain the optimal performance from a transducer. In addition, because of new ultrasound research trends, such as ultrasound systems with other imaging modalities and wireless ultrasound systems, the selection of an appropriate power amplifier could improve the performance of an ultrasound system with other imaging and therapy modalities. This paper describes the design parameters of a power amplifier, including the gain, bandwidth, harmonic distortion, and efficiency. Each power amplifier has specific applications and limitations. Therefore, this review will assist design engineers and ultrasound researchers who need to develop or use power amplifiers in ultrasound applications.

“…Compared to a typical passive filter in the output port of the power amplifier, the proposed harmonic-reduced bias circuit could be helpful to reduce the specific several harmonic distortion components in the echo signals generated by the ultrasound transducer. Especially in the ultrasound applications such as harmonic imaging, acoustic stimulation, and ultrasound therapy, harmonic signal reduction is more important than ultrasound imaging applications [55,56].…”

Section: Frequencymentioning

confidence: 99%

Harmonic-Reduced Bias Circuit for Ultrasound Transducers

2023

Sensors

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The gain of class-C power amplifiers is generally lower than that of class-A power amplifiers. Thus, higher-amplitude input voltage signals for class-C power amplifiers are required. However, high-amplitude input signals generate unwanted harmonic signals. Therefore, a novel bias circuit was proposed to suppress the harmonic signals generated by class-C power amplifiers, which improves the output voltage amplitudes. To verify the proposed idea, the input harmonic signals when using a harmonic-reduced bias circuit (−61.31 dB, −89.092 dB, −90.53 dB, and −90.32 dB) were measured and were found to be much lower than those when using the voltage divider bias circuit (−57.19 dB, −73.49 dB, −70.97 dB, and −73.61 dB) at 25 MHz, 50 MHz, 75 MHz, and 100 MHz, respectively. To further validate the proposed idea, the pulse-echo measurements were compared using the bias circuits. The peak-to-peak echo amplitude and bandwidth of the piezoelectric transducer, measured when using a harmonic-reduced bias circuit (27.07 mV and 37.19%), were higher than those achieved with a voltage divider circuit (18.55 mV and 22.71%). Therefore, the proposed scheme may be useful for ultrasound instruments with low sensitivity.