Techniques related to signal processing include setting up a first operation mode or a second operation mode. In the first operation mode: providing a first analog signal to a first A/D converter by a first switch and a second analog signal to a second A/D by second switch, and converting the first analog signal to a first digital signal by the first A/D and the second analog signal to a second digital signal by the second A/D. In the second operation mode: demodulating a third analog signal to an in-phase signal and a quadrature signal by an I-Q-demodulator, providing the in-phase signal to the first A/D by the first switch, providing the quadrature signal to a second A/D by second switch, converting the in-phase signal to a third digital signal by the first A/D, and converting the quadrature signal to a fourth digital signal by the second A/D.