A biopotential signal acquisition system comprising: an analogue readout unit configured to receive an analogue biopotential signal and to extract an analogue measured biopotential signal and an analogue reference signal; an ADC unit configured to provide a digital version of the analogue measured biopotential signal and the analogue reference signal (DREF); a digital filter unit configured to calculate a digital motion artifact estimate; characterized in that the ADC unit is a Sigma-Delta ADC; the biopotential signal acquisition system comprises a first digital filter unit connected to the output of the Sigma-Delta ADC unit and comprising a cascaded integrator-comb filter, a halfband decimation filter connected to the cascaded integrator-comb filter and a finite impulse response filter connected to the halfband decimation filter, and wherein the first digital filter unit is configured to provide a first digital filtered version (DBS2', DREF') of the digital measured biopotential signal and the reference signal (DREF) at an output of the cascaded integrator-comb filter, and a second digital filtered version (FBS2, FREF) of the digital measured biopotential signal and the digital reference signal (DREF) at an output of the first digital filter unit; and said digital filter unit constitutes a second digital filter unit and is connected to the output of the cascaded integrator-comb filter of the first digital filter unit, and is configured to calculate a digital motion artifact estimate based on said first digital filtered version signals (DBS2', DREF') of the digital measured biopotential signal and the digital reference (DREF). an analogue readout unit configured to receive an analogue biopotential signal and to extract an analogue measured biopotential signal and an analogue reference signal; an ADC unit configured to provide a digital version of the analogue measured biopotential signal and the analogue reference signal (DREF); a digital filter unit configured to calculate a digital motion artifact estimate; characterized in that the ADC unit is a Sigma-Delta ADC; the biopotential signal acquisition system comprises a first digital filter unit connected to the output of the Sigma-Delta ADC unit and comprising a cascaded integrator-comb filter, a halfband decimation filter connected to the cascaded integrator-comb filter and a finite impulse response filter connected to the halfband decimation filter, and wherein the first digital filter unit is configured to provide a first digital filtered version (DBS2', DREF') of the digital measured biopotential signal and the reference signal (DREF) at an output of the cascaded integrator-comb filter, and a second digital filtered version (FBS2, FREF) of the digital measured biopotential signal and the digital reference signal (DREF) at an output of the first digital filter unit; and said digital filter unit constitutes a second digital filter unit and is connected to the output of the cascaded integrator-comb filter of the first digital filter unit, and is configured to calculate a digital motion artifact estimate based on said first digital filtered version signals (DBS2', DREF') of the digital measured biopotential signal and the digital reference (DREF).