Phase noise analysis of a homodyne radar system driven by a phase-locked loop

An analytical model is presented to calculate phase noise spectrum and jitter of a radar system driven by a phase-locked loop (PLL). The high-pass filtered phase noise of the voltage-controlled oscillator (VCO) is modelled as an Ornstein-Uhlenbeck process. For a triangular FMCW frequency sweep, a non-stationary process is used to calculate the PLL output phase. A condition for the loop filter capacitance is derived for which the phase noise is a stationary Ornstein-Uhlenbeck process from the beginning of a frequency sweep. For the stationary case, phase noise spectrum and rms phase jitter at the receiver output are calculated analytically. The effect of noise cancellation in the radar receiver on phase noise and jitter is discussed as a function of basic PLL parameters and target distance.