FREQUENCY SYNTHESIZER Russian patent published in 2003 - IPC

FIELD: radio engineering; local oscillators for radio receivers and transmitters. SUBSTANCE: frequency synthesizer has direct digital synthesizer; filter; phase-locked loop circuit set up of variable-frequency oscillator, variable-ratio frequency divider, phase-frequency detector, and low-frequency filter, all ring-connected in series; digital adder; and solver that functions to compute fractional part of division ratio of direct digital frequency synthesizer and also to generate signal that changes coarse frequency control code and signal that changes input code of direct frequency synthesizer. EFFECT: reduced level of parasitic components in output signal spectrum. 1 cl, 1 dwg