A method and devices for controlling a potentiostat control loop circuit to provide an accurate cell voltage for electrochemically sensing a sample, wherein the cell voltage corresponds to a difference between electrode voltages a working electrode and a reference electrode of a three-electrode potentiostat are provided. The devices include a potentiostat control loop circuit having a first amplifier with an output connected to a counter electrode of the three electrode potentiostat and a first input connected to a first potential and a first switched capacitor network including a first capacitance device having a first electrode connected to a second input of the first amplifier. The first switched capacitor network is also operatively connected to the first amplifier for operating in a first mode and a second mode t switchably couple the second input of the first amplifier to the reference electrode of the three-electrode potentiostat. The method includes the step of, in the second mode, coupling the second input of the first amplifier to the reference electrode of the three-electrode potentiostat via the first capacitance device by coupling a second electrode of the first capacitance device to the reference electrode of the three-electrode potentiostat.