A Dual-Band CMOS Standing-Wave Digitally Controlled Oscillator for Automotive Radars
The 22/75-GHz dual-band digitally controlled oscillator based on standing-wave topology is proposed. By properly choosing the capacitance and respective transmission line length, the high- and low-band frequency ratio could exceed 3 in millimeter-wave region. To resolve the low-Q property originated from the varactor, digitally controlled artificial dielectric is applied to provide high-Q digital tuning mechanism. The prototype is fabricated in TSMC 90 nm CMOS technology under 1.2-V supply. It covers 20.6–22.4 GHz and its 1-MHz offset phase noise is -103.2 to -94.4 dBc/Hz at low-band mode. At high-band operation, the output frequency is 74–75 GHz, and the phase noise is -91.2 to -85.4 dBc/Hz at 1-MHz offset. The current consumption for low band and high band is 6 and 14 mA, respectively.