Broadband VCO Phase Noise Sensitivity to Oscillator Circuit

The measurement and simulation results for described VCO topology showed strong correlation between local frequency selective increase of the negative input resistance and the phase noise increasing in the same frequency band. For rigorous oscillator analysis it must be taken in consideration the impact of the varactor nonlinearities with nonlinear transistor input impedance. Active elements should be classified regarding the 1/f noise, because the 1/f noise could be converted to the oscillator phase noise.