A SiGe-Based 240-GHz FMCW Radar System for High-Resolution Measurements

In this paper, a fully integrated silicon-germanium (SiGe)-based compact high-resolution frequency-modulated continuous-wave (FMCW) radar sensor working in a frequency range from 198 to 250 GHz is presented. The wide modulation bandwidth of 52 GHz enables a range resolution better than 3 mm combined with a measurement accuracy in the micrometer regime. Together with a low power consumption of approximately 3.5 W, a high-focusing Teflon lens antenna, and a compact and robust housing, the presented radar system is capable of satisfying the needs of several novel measuring tasks. A compensated measurement accuracy of down to −0.5–0.4 $\mu \text{m}$ is achieved, which is demonstrated by distance measurements using a laser interferometer reference. Additionally, a calibration technique is shown enabling multi-target measurements reaching to the theoretical limit of the range resolution. As the fundamental feedthrough of common frequency doubler architectures cause false targets in the range profile, a dielectric fundamental frequency filter is presented as well, filtering the fundamental feedthrough signal and thus removing the false target, improving the unambiguousness of the presented radar sensor.