Design of a Linear FMCW Radar Synthesizer with Focus on Phase Noise

Abstract

The linear FMCW radar has become more popular in recent years mainly due toadvances in digital signal processing and the good performance of the radar at closeranges. What puts limits to the performance is mainly phase noise. Because trans-mission and reception happen simultaneously, the phase noise will limit the maxi-mum power that should be used and hence also the ability to detect weak targets.By ensuring during the design process that the phase noise is low, the radar s perfor-mance will thus get better. This thesis describes the construction of a FMCW radarfrequency synthesizer where the focus is mainly on phase noise. The functionalityof the circuit is shown to be successful, but there is more phase noise than what ispredicted. Several causes for this are discussed. Important background theory aboutradars, phase noise and phase-locked loops is presented and several simulations areperformed in order to get a better understanding. The conclusion of the work isthat it is not very hard to build a synthesizer, but in order to tweak the phase noiseperformance to be as good as the linear theory tells it to be, careful attention mustbe paid during all stages of the design.