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.
