Dual-band low-phase-noise LC-QVCO using series coupling and switched biasing techniques

An LC-tank quadrature voltage-controlled oscillator (QVCO) is proposed to achieve frequency-band reconfigurability and low phase noise. In this work, phase noise contributed by the 1/f noise of coupling transistors and tail transistors is noticeably reduced when series coupling and switched biasing techniques are simultaneously adopted. The proposed QVCO was implemented in 0.25-μm triple-well CMOS process for K-PCS and WCDMA bands. Measured results showed a phase noise of −117 dBc/Hz at an offset of 1 MHz and a phase-noise figure-of-merit of −172 dBc/Hz while consuming 8.13 mA from a 2-V power supply.