Ultra-High Input Impedance, Low Noise Integrated Amplifier for Noncontact Biopotential Sensing
Ultra-High Input Impedance, Low Noise Integrated Amplifier for Noncontact Biopotential Sensing
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DOI：
10.1109/jetcas.2011.2179419
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发表时间：
2011-12-01
影响因子：
4.6
通讯作者：
Cauwenberghs, Gert
中科院分区：
文献类型：
--
作者：
Chi, Yu M.;Maier, Christoph;Cauwenberghs, Gert
非接触式心电图/脑电图/肌电图电极主要通过电容耦合工作，已被广泛研究用于不显眼的生理监测。以前使用分立现成放大器的实现一直受到手动调谐输入电容中和网络和复杂直流偏置方案的阻碍。我们设计并制造了一个定制集成的非接触式传感器前端放大器，该放大器完全自引导内部和外部寄生阻抗。不需要外部大值电阻的直流稳定性由交流自启动、低漏、片上偏置网络保证。在无中和的情况下，放大器的输入阻抗为60 fF，输入参考噪声为0.05 fA/根Hz，输入参考噪声为200 nV/根Hz，在3.3 V供电电压下，每通道功耗为1.5 μ A。在0.05 Hz以下，电极耦合电容低至0.5 pF时，频率响应稳定。
Noncontact electrocardiogram/electroencephalogram/ electromyogram electrodes, which operate primarily through capacitive coupling, have been extensively studied for unobtrusive physiological monitoring. Previous implementations using discrete off-the-shelf amplifiers have been encumbered by the need for manually tuned input capacitance neutralization networks and complex dc-biasing schemes. We have designed and fabricated a custom integrated noncontact sensor front-end amplifier that fully bootstraps internal and external parasitic impedances. DC stability without the need for external large valued resistances is ensured by an ac bootstrapped, low-leakage, on-chip biasing network. The amplifier achieves, without neutralization, input impedance of 60 fF vertical bar vertical bar 50 T Omega, input referred noise of 0.05 fA/root Hz and 200 nV/root Hz at 1 Hz, and power consumption of 1.5 mu A per channel at 3.3 V supply voltage. Stable frequency response is demonstrated below 0.05 Hz with electrode coupling capacitances as low as 0.5 pF.