Millimeter-wave and terahertz circuits have numerous applications in radars, remote sensing, and next-generation 5G network. Among the THz radars, frequency-modulated continuous-wave (FMCW) topology has drawn attention for imaging and security applications. Comparing the state-of-the-art FMCW radars, most wideband radars are implemented with costly SiGe HBT transistors
with a fmax of ~380 GHz. Transistor scaling increases the fmax of lowcost CMOS technologies, which makes them suitable for highprecision imaging applications such as dental imaging that require wide bandwidth, compactness, and high operation frequency.
In this project, a compact, wideband, and fully integrated CMOS FMCW radar is proposed. A five-stage voltage-controlled ring oscillator (VCRO) is designed, and the fifth harmonic signal is efficiently extracted to achieve wideband and high-frequency signal generation. The radar achieves a 57 GHz tuning range with a peak EIRP of 6.2 dBm and a 5.8 dB power variation, the lowest power
fluctuation of reported FMCW radars from the 200-400 GHz range. The radar is further used and tested in a dental imaging setup to capture the teeth cavities and root canals.
We have published a paper on IEEE CICC based on this project.