Analysis of noise properties of hybrid frequency synthesizer with autocompensating phase noise of DDS and PLL

We consider a structural diagram of the hybrid frequency synthesizer (HFS) with autocompensating of phase noise of direct digital synthesizer (DDS) and phase-locked loop (PLL). Suppression of the HFS interference is carried out by changing the delay of the DDS output signal in a controlled phase shifter. General equations for the analysis of noise characteristics of HFS are obtained on the basis of the transfer functions of the device for phase fluctuations. The graphs of spectral density of phase noise of individual blocks of a hybrid synth with different regulating coefficients of autocompensating paths of DDS and PLL were drawn.