Transmitter device having a modulation closed loop

The invention relates, inter alia, to a transmitter device, in particular for a base transceiver station in a mobile radio system, which has a digital modulator for making available a signal containing a phase information, and a modulation closed loop having a digital phase comparator operating at baseband whose first input is connected to the output of the digital modulator. In addition, a controllable oscillator is provided for generating an RF transmission signal at a controllable transmission frequency, a device which is assigned to the controllable oscillator and has the purpose of converting the RF transmission signal into a baseband signal containing a phase information. The output of the converter device is connected to a second input of the digital phase comparator. A GSM transmitter which has such a modulation closed loop exhibits, in terms of its out-band noise and interference characteristics, significantly improved properties in comparison with a GSM transmitter which does not include a modulation loop.