Study on X - Ku band voltage controlled oscillators

Abstract

In this thesis, we have proposed and implement several types of VCOs covering X band to Ku band. The proposed VCOs include the balanced VCO, the mode-switched dual-band VCO, the transformer resonator coupled CMOS VCO and the frequency divided and multiplied VCOs. The topology comparison of the balanced and the differential VCOs give important insights of Ku Band VCO design. The noise performances of these VCOs are compared using analytic noise model and experiments. The balanced VCO has higher immunity to the several noise sources that incur in active and passive devices than the differential VCO. The balanced VCO achieves the phase noise of _90.5 dBc and _113.8 dBc at 100 kHz and 1 MHz offset frequency from the carrier of 14 GHz. Its phase performance is ~ 2.5 dB and ~ 7 dB better than the differential VCOs using a microstrip line inductor and a spiral inductor respectively. It can be mentioned that the balanced topology with a microstrip line inductor is suitable for low phase noise VCO over Ku Band. They are realized on InGaP/GaAs HBT technology. A mode switched dual band VCO is proposed for the first time in Ku band and successfully realized. The VCO has agile re-configurability and fast band switching times less than 20 ns between the bands, respectively. The VCO employing a microstrip line inductor gives the measured phase noises performances of _110 and _108 dBc/Hz at 1MHz offset for 13 and 22 GHz, respectively while drawing 22 mA and 16 mA from a 4-V supply. It can be used in mm wave dual band transceiver. The CMOS VCO over X band frequency is most challenging problem nowadays. The analyses of coupled resonator are presented and a quadrature VCO using novel configurations is proposed. First it uses transformer-coupled resonator and the advantage of coupled resonator is investigated. Second the drain-gate transformer feedback configuration is proposed, which allows VCO have deep switched by the feedback bias level shifting. By turning off switching trans...