This article presents an inverter-based multichannel low-power low-noise neural signal recording amplifier with a novel differential-like operational transconductance amplifier (OTA). The differential-like OTA consists of two asymmetric branches. The inverting branch used for multichannel inputs has more inverters in parallel than that of the noninverting branch used for reference. Two virtual rails with very low impedance are designed in the differential-like OTA to effectively reduce the noise-efficiency-factor (NEF) and crosstalk in input channels. The NEF and the effective average current per channel decreases as the number of channels increases. Furthermore, by optimizing the current ratio of the inverting and the noninverting branches of the OTA, the NEF of the proposed amplifier is minimized and approaches the NEF of an ideal inverter of 2–√/2\sqrt {2}/2 as the channel counts increase to infinity. The area per channel is reduced even more significantly as the channel counts increase. The proposed amplifier architecture with 4-channel, 16-channel, and 64-channel configurations were fabricated and measured. The results show that the noise, power, and area performance were all improved by integrating more channels in parallel. For the 64-channel amplifier, the measured NEF is 0.84, the effective average current per channel is 422 nA and the area per channel is only 0.044 mm2.

中文翻译：

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具有新型类差分 OTA 的 64 通道基于逆变器的神经信号记录放大器，NEF 达到 0.84


本文提出了一种基于逆变器的多通道低功耗低噪声神经信号记录放大器，具有新颖的类差分运算跨导放大器 (OTA)。类差分 OTA 由两个不对称分支组成。用于多通道输入的反相支路比用于参考的同相支路具有更多的并联反相器。类差分 OTA 中设计了两条阻抗极低的虚拟轨，可有效降低输入通道中的噪声效率因数 (NEF) 和串扰。每个通道的 NEF 和有效平均电流随着通道数量的增加而减小。此外，通过优化 OTA 的反相和同相支路的电流比，所提出的放大器的 NEF 被最小化，并接近作为通道的理想反相器 2–√/2\sqrt {2}/2 的 NEF计数增加到无穷大。随着通道数量的增加，每个通道的面积会更加显着地减少。所提出的具有 4 通道、16 通道和 64 通道配置的放大器架构已被制造和测量。结果表明，通过并行集成更多通道，噪声、功耗和面积性能均得到改善。对于64通道放大器，测得的NEF为0.84，每通道的有效平均电流为422 nA，每通道的面积仅为0.044 mm2。