Oscillator with odd- symmetrical characteristics eliminates low-frequency noise sidebands

Low-frequency noise in an oscillator normally produces two LF noise sidebands around the center frequency
f_{0}
of the oscillator. It was shown experimentally that these noise sidebands can be eliminated by using an oscillator circuit with an odd-symmetrical characteristic. A simple theory based on the van der Pol approach to oscillators can explain the observed effects.