Range Resolution Improvement in FMCW Radar Through VCO's Nonlinearity Compensation

In order to achieve good range resolution and accuracy on frequency-modulated continuous-wave (FMCW) radars, highly linear chirps are necessary. Voltage-controlled oscillators (V COs) present nonlinearities in their tuning curve. Then, once VCOs are a fundamental building block in many continuous-wave radar systems, these nonlinearities translate into negative effects in terms of range resolution performance. A common approach to generating linear tuning curves is to connect the system VCO to a phase-locked loop (PLL). Although, PLLs increase the system complexity and cost. This work presents a way to improve the range resolution in a portable and low-cost C-band FMCW radar system. The radar VCO is driven by a microcontroller that applies a customized waveform developed to compensate for the nonlinear behavior to achieve such results.