Device for reducing the parasitic lines of the output signal of a digital frequency synthesizer.

摘要

P The invention relates to a device for reducing parasitic lines of the output signal of a digital frequency synthesizer (10) receiving on the one hand a signal (E) coming from a modulator (11) and supplying a signal output (Sdds) at a pure frequency (FS) modulated by spurious frequencies. The device comprises a frequency demodulator (13) receiving the output signal from the synthesizer (10) and providing a correction signal whose amplitude (Vm) is a function of the frequency excursion of the output signal (Sdds) of the synthesizer (10), this correction signal being applied to the modulator (11) so that it modulates the signal applied to the synthesizer (10) in phase opposition with respect to the parasitic modulation, so as to suppress this parasitic modulation. / P