title: Simplified phase noise model for negative-resistance oscillators and a comparison with feedback oscillator models.
abstract: This paper describes a greatly simplified model for the prediction of phase noise in oscillators which use a negative resistance as the active element. It is based on a simple circuit consisting of the parallel addition of a noise current, a negative admittance/resistance, and a parallel (Qlimited) resonant circuit. The transfer function is calculated as a forward trans-resistance (VOUT/IIN) and then converted to power. The effect of limiting is incorporated by assuming that the phase noise element of the noise floor is kT/2, i.e., -177 dBm/Hz at room temperature. The result is the same as more complex analyses, but enables a simple, clear insight into the operation of oscillators. The phase noise for a given power in the resonator appears to be lower than in feedback oscillators. The reasons for this are explained. Simulation and experimental results are included.
authors.affiliation: University of York, York, UK. jkae@ohm.york.ac.uk
authors.forename: Jeremy
authors.initials: J
authors.lastname: Everard
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Simon
authors.initials: S
authors.lastname: Bale