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System for acquiring signals

active electrodes electroencephalographycommon mode rejectioncommon mode voltageelectrocardiographyInformatica Tsd En


In the context of electromedical or electrical measurement instrumentation, the invention relates to a system for the acquisition of potentials deriving, for example, from electroencephalographic or electrocardiographic signals and comprises a circuit able to significantly reduce common mode interferences.

Technical features

The present invention is based on the use of two electrodes reducing the common mode interference which reaches the inputs of the acquisition system. The latter can essentially be a standard instrument for the acquisition of bio-potentials and the invention can easily be integrated as a sub-system of the instrument itself.

The system allows to reduce the common mode interference by 60-80 dB compared to the native system. As a result, active electrodes can be designed allowing for a substantially higher gain rather without degrading the CMRR of the system.

Possible Applications

  • Electromedical instrumentation;
  • Any electrical measurement instrumentation requiring a high common mode rejection ratio.


  • Substantial absence of constraints limiting the common mode rejection;
  • Relaxation of CMRR specifications of the amplification circuits;
  • Single-ended amplification of signals from different electrodes.