engleski

Analog Frontend for ECG/EMG Capacitive Electrodes

In this paper, a complete analog frontend for ECG/EMG signal acquisition through non-contact capacitive electrodes is designed. The main part of the analog signal acquisition chain is a low noise, low input bias current preamplifier, which was designed in both bootstrapped and transimpedance amplifier configurations. The preamplifier is followed by the cascade of active 2nd order high-pass filter with a 20 dB gain and 4th order active low-pass Sallen-Key filter using Butterworth approximation and 40 dB gain. The effects of coupling capacitance on system noise and gain-frequency response for both preamplifier topologies are investigated. The simulated input- referred noise, with a coupling capacitance value equal to 100 pF, for both preamplifier topologies has the value of 2.9 μVRMS . The gain-frequency response of bootstrapped preamplifier achieved greater resilience to variation of coupling capacitance value compared to transimpedance amplifier configuration, especially for lower values of coupling capacitance.

Capacitive sensing , analog frontend , ECG , EMG , non-contact

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