Ultra-High Input Impedance, Low Noise Integrated Amplifier for Noncontact Biopotential Sensing
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...
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Veröffentlicht in: | IEEE journal on emerging and selected topics in circuits and systems 2011-12, Vol.1 (4), p.526-535 |
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Sprache: | eng |
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Zusammenfassung: | 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 \Vert 50 T \Omega , input referred noise of 0.05 fA/ \sqrt{\rm Hz} and 200 nV/ \sqrt{\rm 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. |
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ISSN: | 2156-3357 2156-3365 |
DOI: | 10.1109/JETCAS.2011.2179419 |