Semiconductor device and noise sources modeling: design methods and tools oriented to nonlinear H.F. oscillator CAD

Abstract

Designing oscillator circuits at RF and microwaves requires specific knowledge in extremely varied fields of electronics.The following items will be the core of the presentation: -The physical processes leading to low-frequency noise in semi-conductor devices and the nonlinear behavior of the noise sources in large signal operating conditions will be detailed -Transistor modeling: A special emphasis will be put on the low-frequency noise modeling associated to the nonlinear transistor models. -Simulations tools: In order to simulate accurately the phase noise in free-running nonlinear oscillator circuits, the frequency domain approach based on the conversion matrices formalism which is related to the harmonic balance formalism will be detailed. -Design rules for low phase noise operation Theoretical conditions to be fulfilled by the circuit will be detailed on the basis of the Leeson analysis revisited. The need of new characterizations and extraction methods of noise sources in actual transistors, for a better prediction of noise performances of nonlinear circuits will be recalled.

An Analytic Circuit-Based Model for White and Flicker Phase Noise in <emphasis emphasistype="italic">LC</emphasis> Oscillators

“…If the voltage across the tank is given by then the autocorrelation of the voltage for stationary Gaussian noise processes is given by (see derivation in Appendix II) (7) and represent the autocorrelation functions of the amplitude deviation and the phase , respectively. As is verified in Appendix III, and are stationary processes for the noise processes considered in this paper under the assumption that the oscillator is on for a long enough time.…”

“…The fact that an oscillator can be linearized about its operating point is very much a valid concept as has been demonstrated in numerous papers [7]. We rely on the Kurokawa theory [8] for this purpose.…”

Temporal Modelling of Phase Noise in an Oscillator

“…The generation of the oscillator's noise spectrum being by nature an random process, it's necessary to know on one hand the statistical properties of the oscillator's noise sources and on the other hand the electric interaction between these (random) sources and the linear and not linear elements (determinists) of the circuit which engenders uncertainties of amplitude and phase in a free oscillator [1]. The knowledge of the stationary or not stationary nature of the considered random processes is necessary to define the variations of spectral amplitude or auto-correlation function.…”