The invention relates to a circuit configuration for direct modulation that comprises an oscillator (1) whose output signal is split into quadrature components (LOI, LOQ) for modulation with the useful signal. A circuit (10) used for frequency shifting renders the output frequency and the frequency of the oscillator (1) to be fractional rational multiples of one another. Said circuit (10) comprises a phase shifter (11) that generates first additional quadrature components (S1I, S1Q) and a divider (12) that generates second additional quadrature components (S2I, S2Q). The quadrature components (S1I, S2I; S1Q, S2Q) are mixed with one another (13, 14). The frequency shift results in the oscillation frequency of the oscillator (1) to be shifted towards outside the useful frequency band. Remodulation effects do not influence the adjacent channels. The inventive circuit can be produced in a simple and inexpensive manner, particularly, it requires only one oscillator (1).