You Kiheum, Choi Hojong
Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea.
Sensors (Basel). 2020 Nov 2;20(21):6244. doi: 10.3390/s20216244.
Piezoelectric transducers are triggered by the output voltage signal of a transmit voltage amplifier (TVA). In mobile ultrasound instruments, the sensitivity of piezoelectric transducers is a critical parameter under limited power supply from portable batteries. Therefore, the enhancement of the output voltage amplitude of the amplifier under limited power supply could increase the sensitivity of the piezoelectric transducer. Several-stage TVAs are used to increase the voltage amplitude. However, inter-stage design issues between each TVA block may reduce the voltage amplitude and bandwidth because the electronic components of the amplifier are nonlinearly operated at the desired frequency ranges. To compensate for this effect, we propose a novel inter-stage output voltage amplitude improvement (OVAI) circuit integrated with a class-B TVA circuit. We performed fundamental A-mode pulse-echo tests using a 15-MHz immersion-type piezoelectric transducer to verify the design. The echo amplitude and bandwidth when using an inter-stage OVAI circuit integrated with a class-B TVA circuit (696 mV and 29.91%, respectively) were higher than those obtained when using only the class-B TVA circuit (576 mV and 24.21%, respectively). Therefore, the proposed OVAI circuit could be beneficial for increasing the output amplitude of the class-B TVA circuit for mobile ultrasound machines.
压电换能器由发射电压放大器（TVA）的输出电压信号触发。在移动超声仪器中，压电换能器的灵敏度是在便携式电池供电有限的情况下的一个关键参数。因此，在有限电源供应下提高放大器的输出电压幅度可以提高压电换能器的灵敏度。采用多级TVA来增加电压幅度。然而，每个TVA模块之间的级间设计问题可能会降低电压幅度和带宽，因为放大器的电子元件在所需频率范围内是非线性工作的。为了补偿这种影响，我们提出了一种与乙类TVA电路集成的新型级间输出电压幅度改善（OVAI）电路。我们使用15MHz的浸入式压电换能器进行了基本的A模式脉冲回波测试，以验证该设计。当使用与乙类TVA电路集成的级间OVAI电路时，回波幅度和带宽（分别为696mV和29.91%）高于仅使用乙类TVA电路时获得的回波幅度和带宽（分别为576mV和24.21%）。因此，所提出的OVAI电路可能有利于增加移动超声设备的乙类TVA电路的输出幅度。
