Recent developments in frequency synthesizers in Russia

Frequency Synthesizers (FS) are often used in almost all modern communication systems. The problem of generating some stable frequencies with definite frequency step in VHF, UHF and EHF bands is achieved by using the microwave FS. The different structures of microwave Frequency Synthesizers and classification are considered. The Phase Locked Loop systems (PLL) and pulse PLL are the basic structures for designing the most FS. The general difficulties of designing and investigations are considered for the main structures of microwave FS based on PPL and others.