An improved, analog closed loop linearizer for W and Ka band FMCW

Abstract

FMCW sensors are gaining more importance-in a wide variety of applications for measuring target range and relative velocity. In order to improve resolution of the sensor for measuring between two close, adjacent targets, one has to widen the bandwidth and to improve the linearity of the transmit chirp. In addition, improving the linearity increases the signal to noise ratio, and thus, the receiver sensitivity. In this paper we present a new analog, closed loop system, which pins the higher order VCO nonlinearity resulting in an overall linearity of 0.1%. The system is compact, cheap to implement, and free from spurious signals. Our theoretical analysis also identifies the important parameters which influence the linearity and sensitivity of the receiver.