Device for determining a rotor angle (α) of a rotating shaft, comprising: - a first stator winding, - a second stator winding, the winding axis thereof being at a right angle to the winding axis of the first stator winding, - a rotor winding connected to the rotating shaft for conjoint rotation, - means for applying a carrier signal to the rotor winding such that in each of the first and second stator winding one respective signal (UI1, UI2) is induced, the frequency thereof being consonant with the carrier signal frequency (fe) and the amplitude thereof modulated with the rotor angle, - a first analog-to-digital converter to convert the signal induced in the first stator winding to a first digitized value, - a second analog-to-digital converter to convert the signal induced in the second stator winding to a second digitized value, and - an evaluation device to determine the rotor angle based on the first and the second digitized values, - the first analog-to-digital converter and the second analog-to-digital converter each comprising: - a sigma-delta modulator to output a serial bitstream with a predetermined bit repetition frequency in response to the signal induced in the corresponding stator winding, and - a digital demodulator (9, 10), characterized in that - the digital demodulator is configured to perform demodulation of the serial bitstream output by the sigma-delta modulator or of bitstream-multibit-datawords derived from the serial bitstream, in that the serial bitstream or the bitstream-multibit-datawords are mixed with mixer-multibit-datawords at the bit repetition frequency, wherein the mixer-multibit-datawords correspond to a sampled sinusoidal signal having the carrier signal frequency in digital representation. - a first stator winding, - a second stator winding, the winding axis thereof being at a right angle to the winding axis of the first stator winding, - a rotor winding connected to the rotating shaft for conjoint rotation, - means for applying a carrier signal to the rotor winding such that in each of the first and second stator winding one respective signal (UI1, UI2) is induced, the frequency thereof being consonant with the carrier signal frequency (fe) and the amplitude thereof modulated with the rotor angle, - a first analog-to-digital converter to convert the signal induced in the first stator winding to a first digitized value, - a second analog-to-digital converter to convert the signal induced in the second stator winding to a second digitized value, and - an evaluation device to determine the rotor angle based on the first and the second digitized values, - the first analog-to-digital converter and the second analog-to-digital converter each comprising: - a sigma-delta modulator to output a serial bitstream with a predetermined bit repetition frequency in response to the signal induced in the corresponding stator winding, and - a digital demodulator (9, 10), - a sigma-delta modulator to output a serial bitstream with a predetermined bit repetition frequency in response to the signal induced in the corresponding stator winding, and - a digital demodulator (9, 10), - the digital demodulator is configured to perform demodulation of the serial bitstream output by the sigma-delta modulator or of bitstream-multibit-datawords derived from the serial bitstream, in that the serial bitstream or the bitstream-multibit-datawords are mixed with mixer-multibit-datawords at the bit repetition frequency, wherein the mixer-multibit-datawords correspond to a sampled sinusoidal signal having the carrier signal frequency in digital representation.