Modeling and simulation of PLL-based frequency-synthesizers for FMCW radar

Modeling and simulation of phase-locked loops as important building blocks in many of today´s radio-frequency circuits has been a topic of research for the past decades. The capability to directly apply frequency-modulation to the generated signal by fractional-N-techniques suggests the use of phase-locked loops for signal generation in frequency-modulated continuous wave radar systems, where a periodic modulation scheme is employed. Common modeling approaches either apply simplifications at an early stage of development, or do not consider the specifics of periodic excitations. In this paper an approach is shown that takes the periodic nature of the input into account, on which a simulation of the periodic steady-state of the system is based. Results from simulation of a radar frequency- sweep generated by a non-linear phase-locked loop are presented.