This paper investigates the design of switched-capacitor filters for reconfigurable frequency synthesizer dedicated to FMCW radar. Simulations mixing electronics level and systems level demonstrates that it is possible to generate a chirp waveform with performances close to the one obtained with an ideal continuous-time filter. This chirp waveform is simulated in a simplified FMCW radar model to evaluate effects of the imperfection on the radar. The motivation of this work is the design of reconfigurable and digitally controlled FMCW source based on free-running VCO.