A x2 coupled Colpitt VCO with ultra low phase noise

A coupled Colpitt voltage controlled oscillator, optimized for ultra low phase noise has been designed, fabricated, and characterized. The phase noise is minimized by maximizing the amplitude of the tankvoltage and the Q-value of the tank, optimizing the collector current waveform, and minimizing the loading of the VCO. The VCO works at 13 GHz, the minimum measured phase noise is -120 dBc@100 kHz. This is the lowest reported phase noise to date for a VCO with a fully integrated tank if the 6 dB/octave slope for frequency multiplication is taken into account when comparing VCOs working at different frequencies.