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, and an ADC unit configured to provide a digital version of the analogue measured biopotential signal and the analogue reference signal. The system also includes a first digital filter unit comprising a cascaded integrator-comb filter configured to provide a first digital filtered version of the digital measured biopotential signal and the reference signal, and a second digital filter unit configured to calculate a digital motion artifact estimate based on the first digital filtered version signals.