A sigma-delta modulator can be used for actuating a sensor element. The sigma delta modulator includes: a forward branch to which an input signal is fed at an input and which includes a loop filter, a quantizer and an output for providing an output signal. A feedback branch is configured to feed back the output signal of the forward branch at least temporarily to the input of the forward branch. A signal source is configured to generate a readout signal which corresponds to the voltage profile at the sensor element during a measuring process. A control unit is configured to generate a control signal dependent on which either the output signal of the forward branch or the readout signal of the signal source is fed back to the input of the forward branch.