A-189 dBc/Hz FoMT Wide Tuning Range VCO Using Q-Factor Enhancement Technique

A 28-GHz voltage-controlled oscillator (VCO) with a wide tuning range and a low phase noise is presented in this paper. A PMOS-only cross-coupled pair with a lower flicker noise is exploited to provide the negative resistance. The mechanisms for enhancing the Q-factor of the LC tank at millimeter-wave (mm-wave) frequencies are analyzed and applied to optimize the proposed VCO design to obtain a low phase noise. To guarantee accurate oscillating frequencies, distributed interconnections are carefully modeled by EM simulations. Fabricated in a standard 90-nm CMOS process, the proposed VCO achieves a wide tuning range of 20.1 %, from 25 to 30.66 GHz and a low phase noise of −105.47 dBc/Hz at 1-MHz offset. The current of the core circuit is 10.5 mA under a single 1.2-V supply. The core area of the chip is 0.38 mm × 0.24 mm.