IEEE Trans Biomed Circuits Syst. 2007 Sep;1(3):184-92. doi: 10.1109/TBCAS.2007.914490.
We present in this paper a low-power bioamplifier suitable for massive integration in dense multichannel recording devices. This bioamplifier achieves reduced-size compared to previous designs by means of active low-frequency suppression. An active integrator located in the feedback path of a low-noise amplifier is employed for placing a highpass cutoff frequency within the transfer function. A very long integrating time constant is achieved using a small integrated capacitor and a MOS-bipolar equivalent resistor. This configuration rejects unwanted low-frequency contents without the need for input RC networks or large feedback capacitors. Therefore, the bioamplifier high-input impedance and small size are preserved. The bioamplifier, implemented in a 0.18-mum CMOS process, has been designed for neural recording of action potentials, and optimised through a transconductance-ef-ficiency design methodology for micropower operation. Measured performance and results obtained from in vivo recordings are presented. The integrated bioamplifier provides a midband gain of 50 dB, and achieves an input-referred noise of 5.6 muVrms. It occupies less than 0.050 mm(2) of chip area and dissipates 8.6 muW.
我们在本文中提出了一种适用于密集多通道记录设备的低功耗生物放大器。与以前的设计相比，这种生物放大器通过主动抑制低频来实现小型化。在低噪声放大器的反馈路径中采用有源积分器，在传递函数中设置高通截止频率。通过使用小集成电容器和 MOS 双极等效电阻，可以实现非常长的积分时间常数。这种配置无需输入 RC 网络或大反馈电容器即可拒绝不需要的低频内容。因此，保持了生物放大器的高输入阻抗和小尺寸。该生物放大器采用 0.18 微米 CMOS 工艺实现，专为动作电位的神经记录而设计，并通过跨导效率设计方法进行了优化，以实现微功耗操作。本文介绍了测量性能和体内记录的结果。集成的生物放大器提供 50dB 的中频增益，并实现 5.6μVrms 的输入参考噪声。它占用的芯片面积小于 0.050mm(2)，功耗为 8.6μW。
