The invention relates to a communication transmitter (100) for transmitting a communication signal including a plurality of frequency channels, the plurality of frequency channels comprising a first frequency channel situated around a frequency fRF1 and a second frequency channel situated around a frequency fRF2 and defining a mutual spectral range of interest having a spectral bandwidth Δf and being situated around a frequency fRF. The communication transmitter (100) comprises: a first modulator (103a) being configured to modulate a first base band frequency channel on the basis of a first local oscillator frequency fLO1 to obtain a first modulated signal including the first frequency channel; a second modulator (103b) being configured to modulate a second base band frequency channel on the basis of a second local oscillator frequency fLO2 to obtain a second modulated signal including the second frequency channel; a first combiner (105) being configured to add the first modulated signal and the second modulated signal to obtain a combined modulated signal; and a mixer (107) being configured to mix the combined modulated signal with a periodic mixing signal having a mixing frequency fc for generating the communication signal, wherein the communication signal comprises the down-converted first frequency channel of the combined modulated signal and the up- converted second frequency channel of the combined modulated signal. A particular merit of this invention is its superior immunity to LO pulling and crosstalk that impair the performance of prior art parallel processing transmitters.