A circuit arrangement for a multimode mobile telephone that transmits and receives signals to and from various mobile radio networks contains a baseband and a transceiver unit. The transceiver unit includes a digital adaptive predistorter having a switching element. The switching element is arranged so that an optional connection is created. The optional connection connects an amplifier output to an input of a receiver causing that receiver input to be disconnected from an antenna changeover switch. This way, it is possible for the receiver to be disconnected from a transmitting and receiving antenna during periods when the receiver is not receiving signals from the transmitting and receiving antenna. While the receiver is disconnected from the transmitting and receiving antenna, the receiver is able to receive other signals. By using a simple switch the receiver can be disconnected from the transmitting and receiving antenna, and at the same time establish a connection between the output of the transmitter amplifier and the input of the receiver. By doing so, the receiver is able to tap off and detect signals at the output of the transmitter amplifier.