This chapter describes the design and the optimization of Quadrature Voltage Controlled Oscillators (QVCOs) based on the coupling of two LC-tank VCO. This work covers the phase noise analysis, a graphical optimization approach, already used to optimize LC oscillator phase noise (Andreani, Bonfanti, Romano, & Samori, 2002), to optimize QVCO phase noise while satisfying design constraints such as power dissipation, tank amplitude, tuning range and start up condition. The cross-coupling transistors impact on phase noise for different configurations is especially addressed. The obtained BS-QVCO, using 0.35µm CMOS process, can be tuned between 2.2GHz and 2.58GHz, and shows a phase noise of -129 dBc/Hz at 1MHz offset from a 2.4 GHz carrier, for a current consumption of 9.25mW. The equivalent phase error and amplitude error between I and Q signals are respectively 0.65° and 1.87%.
An In-Phase-Coupled Class-C Quadrature VCO With Tunable Phase Error
