Research on the method for producing a highly linear FMCW signal based on the PLL circuits

This paper describes a method for directly generating FMCW signal based on the PLL circuits; mainly by changing the PLL system´s frequency divider ratio N rapidly and producing a corresponding control voltage to control VCO to output the FMCW signal. The key of this method is the transition period Δt of divider. Set up simulation model in ADS2011 to simulate, get the conclusion that the smaller the transition period Δt, the better the linearity of the FMCW signal than verify this conclusion by measurement. This method has many characteristics like high reliability, easy to adjust, mature circuit structure, etc.