Background Noise in Nonlinear Oscillators

For a general black box model of a resistive one terminal-pair nonlinear oscillator, it is shown that the noise output from noise bands around the oscillatory frequency is composed of an additive noise of the shape of the oscillator resonant circuit and a very small FM broadening of the oscillator line. A noise generator across the oscillator terminals will produce the same amount of additive noise in the load as if the nonlinearity were absent, but the upper and lower sidebands are fully correlated, not independent as in the linear case. The noise bandwidth of the additive noise can be determined by the passive elements and the change in oscillator output power with changing load conductance at the operating load conductance. When the load conductance is adjusted for maximum oscillator output power, the noise bandwidth is the same as if the value of load conductance gave maximum power from a linear circuit.