Linearity study of DDS-based W-band FMCW sensor

The linearity of a W-band frequency-modulated continuous-wave (FMCW) sensor is characterized and its impact on the range resolution of the sensor is evaluated in this paper. The millimeter-wave (mm-wave) FMCW waveform is designed and generated with a direct digital synthesizer (DDS) at base band and transferred to millimeter-wave by a combination of upconversion and multiplication. Both homodyne and heterodyne receiver architectures are studied in this investigation. The sensor linearity is characterized with mm-wave optical-delay line technique under a controlled environment to obtain accurate results.