IEEE Trans Biomed Circuits Syst. 2018 Jun;12(3):700-708. doi: 10.1109/TBCAS.2018.2819207.
This paper presents a low-power and low-noise capacitive-feedback amplifier with a current-reused OTA for ECG recordings. To improve the noise-power efficiency, the proposed OTA employs a current-reused architecture, which adopts an inverter-based differential input stage for low noise, and a class-AB output stage for large output range and high g/I efficiency. The driving branch of the class-AB output stage is merged into the input stage to realize current reuse and reduce power consumption further. Fabricated in a 0.35-μm CMOS process, the amplifier consumes 160 nA from a 2-V supply, while achieving an input-referred noise of 2.05 μV, corresponding to a noise efficiency factor (NEF) of 2.26. The measured common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) exceed 65 dB and 70 dB, respectively. The total harmonic distortion (THD) is less than 1% with a 15-mV input at 20 Hz and the active area is 0.3 mm × 0.6 mm.
本文提出了一种用于 ECG 记录的低功耗、低噪声电容反馈放大器，采用了电流复用 OTA。为了提高噪声功率效率，所提出的 OTA 采用了电流复用架构，采用基于反相器的差分输入级实现低噪声，采用 AB 类输出级实现大输出范围和高 g/I 效率。AB 类输出级的驱动分支与输入级合并，实现电流复用，进一步降低功耗。该放大器采用 0.35μm CMOS 工艺制造，在 2V 电源下消耗 160nA，同时实现了 2.05μV 的输入参考噪声，对应的噪声效率因子（NEF）为 2.26。测量的共模抑制比（CMRR）和电源抑制比（PSRR）分别超过 65dB 和 70dB。在 20Hz 时输入 15mV 的总谐波失真（THD）小于 1%，有源面积为 0.3mm×0.6mm。
