A Direct Bulk Coupling PMOS Colpitts QVCO Using Capacitive-Feedback Structure

In this paper, a full PMOS Colpitts quadrature voltage-controlled oscillator (QVCO) topology, suitable for low supply voltage and low power dissipation, is presented. For an enhanced voltage swing under a low supply voltage, the capacitive-feedback technique is employed. Quadrature coupling is achieved by employing direct bulk coupling technique, leading to reduction in both power and chip area. The proposed QVCO covers a 5% tuning range between 2.325 GHz and 2.435 GHz, and the phase noise is -128.2 dBc/Hz at 1-MHz offset from the 2.34-GHz carrier while consuming only 0.535 mW from 0.55-V supply voltage, yielding a figure-of-merit (FoM) of 198 dBc/Hz.