DEVICE FOR REDUCING PARASITIC SPECTRAL LINE IN OUTPUT SIGNAL FROM DIGITAL FREQUENCY SYNTHESIZER

摘要

PURPOSE: To provide a device for reducing the parasitic spectral line in the output signal from a digital frequency synthesizer. ;CONSTITUTION: A device for reducing the parasitic spectral line in the output signal Sdds from a digital frequency synthesizer 10 which receives a clock signal E outputted from a modulator 11 and supplies the output signal Sdds having a pure frequency FS modulated by means of a parasitic frequency. This device incorporates a frequency demodulator 13 which receives the output signal of the synthesizer 10 and supplies a correction signal whose amplitude Vm is the function of the frequency transition of the output signal Sdds of the synthesizer 10 and which is impressed upon the modulator 11 for modulating the signal impressed upon the synthesizer 10 in the opposite phase against incidental modulation so as to suppress the incidental modulation.;COPYRIGHT: (C)1995,JPO