A fully monolithic SiGe quadrature voltage controlled oscillator design for GSM/DCS-PCS applications

This paper describes the design and optimization in terms of phase noise of a fully monolithic SiGe Voltage Controlled Oscillator (VCO) with quadrature outputs. The proposed circuit is made of two cross-coupled differential VCO's, with integrated resonator, to ensure the quadrature outputs. The quadrature VCO core runs on 13 mA from a 2.7 V power supply. The simulated phase noise is about -140 dBc/Hz at 3 MHz frequency offset almost all over the tuning range. The oscillator is tuned from 1.44 GHz to 1.76 GHz with a tuning voltage varying from 0 to 3 V.