Nonlinear oscillators in Radio Frequency circuits

A wide research has been carried on for radio frequency circuits with nonlinear conductance of quadratic type, the so called Van der Pol oscillators. New technology presents a more general nonlinearity. The aim of this paper is to analyse the main properties of a class of nonlinear oscillators arising in an integrated VCO circuit considered in radio frequency transceivers. The analysis will take in account thermal noise source. This gives an output voltage which is not a sinusoid; in fact the output spectrum is a band. Since high quality mobile communication requires narrow band spectrum, we will show how the parameters of the circuit can be changed in order to reduces the phase noise effects