Effect of process variations in CMOS chips for radar beamforming

The introduction of single chip CMOS radar transceivers offers the possibility of a low cost system for beamforming at close range. With the benefits of low weight, low power and low cost, single chip radars stand to possibly revolutionize a range of close range imaging applications such as land mine detection, through wall imaging and even medical imaging. There are, however some challenges that remain to be overcome in order to produce high quality radar images in real time. One of the main challenges lies in control over the CMOS process to produce a deterministic, uniform and reproducible delay line for sampling the received signal at a very high frequency. This paper gives an overview of possible error sources contributing to the lowering of quality of a radar image with particular focus on the effect of non-uniform sample delays caused by process variations. Finally, a method of direct calibration is presented that corrects some of the quality degradation.