IEEE Trans Ultrason Ferroelectr Freq Control. 2012 Apr;59(4):825-32. doi: 10.1109/TUFFC.2012.2261.
Linear power amplifiers are critical components in ultrasonic imaging systems that implement chirp-coded excitation. Bench-top commercial power amplifiers are usually used in academic laboratories for high-frequency ultrasound imaging, and the imaging performance depends greatly on these general-purpose instruments. To achieve a wide dynamic range, a power amplifier consisting of two stages is developed for chirp-coded ultrasound imaging applications through the implementation of custom-designed broadband 1:1 transformers and the optimization of feedback circuits. The amplifier has broad bandwidth (5 to 135 MHz), maintaining a linearity up to the 1-dB gain compression point (P1dB) of 41.5 dBm, allowing 16 dBm input power level at 60 MHz. The mean and the maximum values of output third-order intercept points (OIP3) are 51.8 and 53.5 dBm, respectively, between 20 and 110 MHz. With 12 dBm input power, the gain of the amplifier varies between 24 and 29 dB, offering a uniformity which would allow excitation of a 70-MHz single-element transducer with windowed chirp-coded bursts sweeping from 40 to 100 MHz. The performance in high-frequency ultrasound imaging is evaluated with a wire phantom. Echo signal-to-noise ratio (eSNR) of the designed amplifier is 7 dB better than a commercial amplifier, and spatial resolution is maintained.
线性功率放大器是实现线性调频激励的超声成像系统的关键组成部分。台式商用功率放大器通常用于高频超声成像的学术实验室，其成像性能在很大程度上取决于这些通用仪器。为了实现宽动态范围，针对线性调频超声成像应用，通过实现定制的宽带 1:1 变压器和反馈电路的优化，开发了由两个级联的放大器组成的功率放大器。该放大器具有较宽的带宽（5 至 135 MHz），在线性度方面保持高达 41.5 dBm 的 1-dB 增益压缩点（P1dB），在 60 MHz 时允许 16 dBm 的输入功率电平。在 20 至 110 MHz 之间，输出三阶截点（OIP3）的平均值和最大值分别为 51.8 和 53.5 dBm。当输入功率为 12 dBm 时，放大器的增益在 24 至 29 dB 之间变化，提供了均匀性，从而可以激励 70 MHz 的单个元件换能器，用从 40 至 100 MHz 的窗式线性调频编码脉冲进行扫频。通过线阵体模评估了在高频超声成像中的性能。与商用放大器相比，设计的放大器的回波信号噪声比（eSNR）提高了 7 dB，且空间分辨率得以保持。
