Jung Sung-Jin, Hong Seong-Kwan, Kwon Oh-Kyong
IEEE Trans Biomed Circuits Syst. 2017 Feb;11(1):108-116. doi: 10.1109/TBCAS.2016.2552246. Epub 2016 Jun 22.
This paper presents a low-noise amplifier (LNA) using attenuation-adaptive noise control (AANC) for ultrasound imaging systems. The proposed AANC reduces unnecessary power consumption of the LNA, which arises from useless noise floor, by controlling the noise floor of the LNA with respect to the attenuation of the ultrasound. In addition, a current feedback amplifier with a source-degenerated input stage reduces variations of the bandwidth and the closed loop gain, which are caused by the AANC. The proposed LNA was fabricated using a 0.18-[Formula: see text] CMOS process. The input-referred voltage noise density of the fabricated LNA is 1.01 [Formula: see text] at the frequency of 5 MHz. The second harmonic distortion is -53.5 dB when the input signal frequency is 5 MHz and the output voltage swing is 2 [Formula: see text]. The power consumption of the LNA using the AANC is 16.2 mW at the supply voltage of 1.8 V, which is reduced to 64% of that without using the AANC. The noise efficiency factor (NEF) of the proposed LNA is 3.69, to our knowledge, which is the lowest NEF compared with previous LNAs for ultrasound imaging.
本文介绍了一种用于超声成像系统的采用衰减自适应噪声控制（AANC）的低噪声放大器（LNA）。所提出的AANC通过根据超声衰减来控制LNA的本底噪声，降低了由无用本底噪声引起的LNA不必要的功耗。此外，一种具有源极退化输入级的电流反馈放大器减少了由AANC引起的带宽和闭环增益的变化。所提出的LNA采用0.18-[公式：见原文]CMOS工艺制造。所制造的LNA在5 MHz频率下的输入参考电压噪声密度为1.01 [公式：见原文]。当输入信号频率为5 MHz且输出电压摆幅为2 [公式：见原文]时，二次谐波失真为-53.5 dB。在1.8 V电源电压下，采用AANC的LNA功耗为16.2 mW，相较于不使用AANC时降低至64%。据我们所知，所提出的LNA的噪声效率因子（NEF）为3.69，与先前用于超声成像的LNA相比，这是最低的NEF。
