Design of Low Phase-Noise Microwave Oscillator and Wideband VCO Based on Microstrip Combline Bandpass Filters
This brief characterizes oneand two-port passive networks from the viewpoint of oscillator design. A linear circuit theory derives the spectral spread due to RF noise from active devices. The formulation finds a frequency derivative function of logarithmic immittance that plays the key role of dominating the spectrum behavior. This leads to an explicit definition of the factor by referring to Leeson’s basic oscillator model. The derived definition can provide an effective criterion for circuit topology and parameter optimization in low-noise oscillator design.