- - AN ACTIVE ELECTRODE HAVING A CLOSED-LOOP UNIT-GAIN AMPLIFIER WITH CHOPPER MODULATION

摘要

The active electrode has an electrode for sensing a potential and generating an input signal, and a shield disposed near the electrode but electrically insulated from the electrode. The integrated amplifier 10 has an input coupled to at least one electrode for providing a buffering path for receiving an input signal and outputting a buffered output signal. The shield is coupled to the output of the integrated amplifier to actively drive the potential of the shield, thereby providing an active shield of the electrode. The buffering path comprises a first mixer 11 in front of the integrated amplifier for frequency shifting the input signal from the fundamental frequency range to a higher frequency range, and for frequency shifting the amplified signal back from the higher frequency range to the fundamental frequency range. A second mixer on the output of the integrated amplifier. Active electrodes can be used to record EEG signals.