A first signal path having an amplifier and a second signal path having an amplifier with adjustable gain factor are provided. A signal applied to the first and second signal paths is amplified and demodulated on the first signal path. Concurrently, the signal is amplified on the second signal path with a gain factor, and a power of the signal amplified by the second signal path is determined and used for determining the gain factor. A signal conditioning circuit has first and second signal paths and a first and a second operating state. In the first operating state, the first signal path is arranged for amplification for a demodulation, and the second signal path is arranged for amplification for determination of a power of the signal present. In the second operating state, one of the two signal paths is inactive and the other is arranged for demodulating the signal present.