A method and device are provided for demodulation of an output signal from a transducer (1) driven by an alternating excitation signal having an excitation frequency. The transducer produces an amplitude-modulated output signal (y(t)) containing the quantity to be measured. The device has sampling units (5,6,7) to sample the output signal from the transducer and the output signal from the excitation unit, and a computation unit (8) to compute a first complex valued quantity ( Y) including information on the amplitude and phase of the output signal at the excitation frequency based on sampled values of the output signal from the transducer, compute a second complex valued quantity (Ū, Ī) including information on the amplitude and phase of the excitation signal at the excitation frequency based on sampled values of the excitation signal, forming a complex valued output quotient between the first and second complex valued quantities, and compute the demodulated output signal (Od) based on the output quotient.