Abstract <p>The architecture of a pulse-continuous model of a multi-detector pulse-phase locked loop system of a frequency synthesizer with frequency dividers with a fractional-variable division coefficient for determining the level of fractional interference is presented. Analytical expressions were obtained and a program was developed in the MATLAB system to determine the level of fractional interference when using a frequency synthesizer of a multiaccumulator. The results of spectral analysis of the output signal phase of a frequency synthesizer in a broadband sampled phase-locked loop system are presented. A method is proposed for determining the level of fractional interference in a frequency synthesizer, taking into account the time quantization of processes in an ideal pulse element using the mathematical model of a frequency synthesizer in the state space. The effect of the spread of the response delays of multiple pulse-phase detectors from the multiaccumulator on the level of fractional interference is analyzed. The results of a spectral analysis of the level of fractional interference using the mathematical model of a frequency synthesizer that takes into account the delay in the operation of a separate pulse-phase detector are presented.</p>