Nonlinearity Estimation and Correction of VCO Based on Temperature-Varied Tuning Characteristic Model

As nonlinearity in voltage controlled oscillator (VCO) degrades the range resolution of frequency modulated continuous wave (FMCW) radar, a novel method to estimate and correct the nonlinearity is presented in this paper. Firstly, in order to provide a more accurate description of the nonlinear term, a temperature-varied tuning characteristic model of VCO (VCO-TT) is built. Afterwards, based on the VCO-TT model, a contrast of range profile optimization algorithm is adopted, which achieves the optimal estimation and correction of the nonlinearity. Without changing hardware system, this method which operates directly on the deramped data can refocus the range profile as well as nonlinearity removal simultaneously. Finally, experimental results from a commercial VCO convincingly validate the feasibility and effectiveness of the proposed method.