Kim Kyeongjin, Choi Hojong
Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-Daero, Gumi 39253, Korea.
Sensors (Basel). 2021 Apr 15;21(8):2795. doi: 10.3390/s21082795.
To obtain a high-quality signal from an ultrasound system through the transmitter, it is necessary to achieve an appropriate operating point of the power amplifier in the ultrasonic transmitter by applying high static bias voltage. However, the power amplifier needs to be operated at low bias voltage, because a power amplifier operating at high bias voltage may consume a large amount of power and increase the temperature of the active devices, worsening the signal characteristics of the ultrasound systems. Therefore, we propose a new method of increasing the bias voltage for a specific period to solve this problem by reducing the output signal distortion of the power amplifier and decreasing the load on the active device. To compare the performance of the proposed method, we measured and compared the signals of the amplifier with the proposed technique and the amplifier only. Notably, improvement was achieved with 11.1% of the power added efficiency and 3.23% of the total harmonic distortion (THD). Additionally, the echo signal generated by the ultrasonic transducer was improved by 2.73 dB of amplitude and 0.028% of THD under the conditions of an input signal of 10 mW. Therefore, the proposed method could be useful for improving ultrasonic transmitter performance using the developed technique.
为了通过发射器从超声系统获得高质量信号，有必要通过施加高静态偏置电压在超声发射器中实现功率放大器的适当工作点。然而，功率放大器需要在低偏置电压下工作，因为在高偏置电压下工作的功率放大器可能会消耗大量功率并提高有源器件的温度，从而恶化超声系统的信号特性。因此，我们提出了一种在特定时间段内增加偏置电压的新方法，以通过减少功率放大器的输出信号失真并减轻有源器件的负载来解决这个问题。为了比较所提出方法的性能，我们测量并比较了采用所提出技术的放大器和仅放大器的信号。值得注意的是，功率附加效率提高了11.1%，总谐波失真（THD）降低了3.23%。此外，在输入信号为10 mW的条件下，超声换能器产生的回波信号的幅度提高了2.73 dB，THD降低了0.028%。因此，所提出的方法对于使用所开发技术提高超声发射器性能可能是有用的。
