A Low-Phase-Noise K-Band CMOS VCO

A novel circuit topology for low-phase-noise voltage
controlled oscillators (VCOs) is presented in this letter. By employing
a PMOS cross-coupled pair with a capacitive feedback,
superior circuit performance can be achieved especially at higher
frequencies. Based on the proposed architecture, a prototype VCO
implemented in a 0.18- m CMOS process is demonstrated for
K-band applications. From the measurement results, the VCO
exhibits a 510-MHz frequency tuning range at 20 GHz. The output
power and the phase noise at 1-MHz offset are 3 dBm and
111 dBc/Hz, respectively. The fabricated circuit consumes a dc
power of 32 mW from a 1.8-V supply voltage.