Patent ID: 7324788

Claim:
An RF integrated circuit of a frequency synthesizer and a QAM modulator for modulating a baseband signal of frequency F BB , the frequency synthesizer supplying to the QAM modulator an output signal of frequency F 1 adjustable with a frequency step ΔF 1 , for forming a carrier signal of the QAM modulator, characterised in that the frequency synthesizer is a Vernier effect frequency synthesizer comprising: an auxiliary frequency synthesizer supplying an auxiliary signal of frequency F 2 adjustable with a frequency step ΔF 2 , and a main frequency synthesizer supplying the output signal of frequency F 1 and having a phase-locked loop for mixing the output signal of frequency F 1 with the auxiliary signal of frequency F 2 , such that the frequency step ΔF 1 of the output signal is equal or proportional to the frequency step ΔF 2 of the auxiliary signal, and in that the bandwidth of the phase-locked loop of the main frequency synthesizer is as least two times higher than the frequency step ΔF 2 of the auxiliary signal.