Department of Electronic Engineering, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam 13120, Gyeonggi-do, Republic of Korea.
Sensors (Basel). 2023 Feb 21;23(5):2406. doi: 10.3390/s23052406.
The ultrasound instrumentation uses linear power amplifiers with low power efficiency, generating unwanted heat and resulting in the deterioration of the echo signal quality of measured targets. Therefore, this study aims to develop a power amplifier scheme to increase power efficiency while maintaining appropriate echo signal quality. In communication systems, the Doherty power amplifier has shown relatively good power efficiency while producing high signal distortion. The same design scheme cannot be directly applied to ultrasound instrumentation. Therefore, the Doherty power amplifier needs to be re-designed. To verify the feasibility of the instrumentation, a Doherty power amplifier was designed to obtain high power efficiency. The measured gain, output 1-dB compression point, and power-added efficiency of the designed Doherty power amplifier were 33.71 dB, 35.71 dB, and 57.24% at 25 MHz, respectively. In addition, the performance of the developed amplifier was measured and tested using the ultrasound transducer through the pulse-echo responses. The output power with 25 MHz, 5-cycle, and 43.06 dB generated from the Doherty power amplifier was sent through the expander to the focused ultrasound transducer with 25 MHz and 0.5″ diameter. The detected signal was sent via a limiter. Afterwards, the signal was amplified by a 36.8 dB gain preamplifier, and then displayed in the oscilloscope. The measured peak-to-peak amplitude in the pulse-echo response with an ultrasound transducer was 0.9698 V. The data showed a comparable echo signal amplitude. Therefore, the designed Doherty power amplifier can improve the power efficiency used for medical ultrasound instrumentation.
超声仪器使用功率效率低的线性功率放大器，会产生不必要的热量，导致被测目标的回波信号质量恶化。因此，本研究旨在开发一种功率放大器方案，在保持适当的回波信号质量的同时提高功率效率。在通信系统中，Doherty 功率放大器在产生高信号失真的情况下表现出相对较好的功率效率。相同的设计方案不能直接应用于超声仪器。因此，需要重新设计 Doherty 功率放大器。为了验证仪器的可行性，设计了一种 Doherty 功率放大器以获得高功率效率。设计的 Doherty 功率放大器在 25MHz 时的增益、输出 1dB 压缩点和功率附加效率分别为 33.71dB、35.71dB 和 57.24%。此外，通过脉冲回波响应使用超声换能器对开发的放大器进行了性能测量和测试。从 Doherty 功率放大器产生的 25MHz、5 个周期和 43.06dB 的输出功率通过扩展器发送到 25MHz 和 0.5 英寸直径的聚焦超声换能器。检测到的信号通过限幅器发送。然后，信号通过增益为 36.8dB 的前置放大器放大，并在示波器上显示。在使用超声换能器的脉冲回波响应中测量到的峰值-峰值幅度为 0.9698V。数据显示出相当的回波信号幅度。因此，设计的 Doherty 功率放大器可以提高用于医学超声仪器的功率效率。
