L-Band SiGe HBT Clapp and Hartley VCOs Using Double Varactor Diodes and Dual-Band Resonators for High Frequency and Wide Bandwidth Oscillations

L-band SiGe HBT Clapp and Hartley VCOs using double varactor diodes and dual-band resonators are presented. These VCOs use dual-band LC resonators for a higher frequency oscillation and double varactor diodes for a wider bandwidth oscillation. The implemented Clapp VCO has demonstrated an oscillation frequency from 1.45 to 1.68GHz and the phase noise at 1MHz offset of better than -120dBc/Hz. As compared with the traditional single-band resonator, the oscillation frequency has achieved 1.5 times higher and the bandwidth 2.1 times wider. Moreover, the implemented Hartley VCO has accomplished an oscillation frequency from 1.306 to 1.345GHz and the phase noise at 1MHz offset of less than -126dBc/Hz. As compared with the traditional single-band resonator, the oscillation frequency has shown 1.37 times higher and the bandwidth 2.5 times wider. This is the first paper on the improvement of an oscillation frequency and a tuning bandwidth of the Clapp and Hartley VCOs by using double varactor diodes and dual-band resonators.