A 1.94 to 2.55 GHz, 3.6 to 4.77 GHz Tunable CMOS VCO Based on Double-Tuned, Double-Driven Coupled Resonators

Date Added: Sep 2009
Format: PDF

This paper presents a multi-band CMOS VCO using a double-tuned, current-driven transformer load. The dual frequency range oscillator is based on enabling/disabling the driving current in the secondary port of the transformer. This approach eliminates the effect of switches connected directly to the VCO tank whose capacitance and on-resistance affect both the tuning range and the phase noise of a typical multi-band oscillator. The relation between the coupling coefficient of the transformer load, selection of frequency bands, and the resulting quality factor at each band is investigated.