A system for impedance measurement comprising: a current generator unit configured to generate a differential alternate current signal (11, 12) that is injected to an element that presents a certain electrical impedance; electrode sensors configured to provide an analogue sensor signal (S1, S2) sensed from that element when said current signal (11, 12) runs through said element; a high-pass filtering unit configured to adapt said analogue sensor signal (S1, S2), so as to reject DC offset, into a filtered analogue signal (IN1, IN2); a calibration circuit comprising a switch matrix connected to a chopper; an analogue impedance readout unit configured to calculate, derived from said filtered signal (IN1, IN2), an impedance value signal (IMP1, IMP2) of the electrical impedance; an ADC unit configured to digitize the impedance signal (IMP1, IMP2) generated by the analogue impedance readout unit; and a DSP unit configured to receive a digital version of the impedance signal (D1, D2) and to store it in a memory unit; characterized in that, in operation during a calibration period, the calibration circuit is configured to activate the chopper and to control the switch matrix in order to disconnect the filtered analog signal (IN1, IN2) from the chopper inputs and to connect a voltage reference signal to the chopper inputs, such that the system is configured to calculate an offset error of the analogue impedance readout unit and the ADC unit, and the DSP unit is configured to store said offset error value (VoffR, Voffl); and during a measurement period, the calibration circuit is configured to deactivate the chopper and to control the switch matrix in order to disconnect the voltage reference signal from the chopper inputs and to connect the filtered analog signal (IN1, IN2) to the chopper inputs, such that the system is configured to measure impedance value signals (IMP1, IMP2) of the electrical impedance, and the DSP unit is configured to calculate an impedance value (R{z},I{z}) by subtracting the offset error value from the measured impedance value. a current generator unit configured to generate a differential alternate current signal (11, 12) that is injected to an element that presents a certain electrical impedance; electrode sensors configured to provide an analogue sensor signal (S1, S2) sensed from that element when said current signal (11, 12) runs through said element; a high-pass filtering unit configured to adapt said analogue sensor signal (S1, S2), so as to reject DC offset, into a filtered analogue signal (IN1, IN2); a calibration circuit comprising a switch matrix connected to a chopper; an analogue impedance readout unit configured to calculate, derived from said filtered signal (IN1, IN2), an impedance value signal (IMP1, IMP2) of the electrical impedance; an ADC unit configured to digitize the impedance signal (IMP1, IMP2) generated by the analogue impedance readout unit; and a DSP unit configured to receive a digital version of the impedance signal (D1, D2) and to store it in a memory unit; characterized in that, in operation during a calibration period, the calibration circuit is configured to activate the chopper and to control the switch matrix in order to disconnect the filtered analog signal (IN1, IN2) from the chopper inputs and to connect a voltage reference signal to the chopper inputs, such that the system is configured to calculate an offset error of the analogue impedance readout unit and the ADC unit, and the DSP unit is configured to store said offset error value (VoffR, Voffl); and during a measurement period, the calibration circuit is configured to deactivate the chopper and to control the switch matrix in order to disconnect the voltage reference signal from the chopper inputs and to connect the filtered analog signal (IN1, IN2) to the chopper inputs, such that the system is configured to measure impedance value signals (IMP1, IMP2) of the electrical impedance, and the DSP unit is configured to calculate an impedance value (R{z},I{z}) by subtracting the offset error value from the measured impedance value.