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Theory of perturbed negative conductance oscillators
Author(s) -
Thirup G.
Publication year - 1986
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.4490140202
Subject(s) - vackář oscillator , variable frequency oscillator , voltage controlled oscillator , local oscillator , delay line oscillator , physics , oscillator phase noise , perturbation (astronomy) , digitally controlled oscillator , voltage , mathematics , mathematical analysis , phase noise , quantum mechanics , optics , optoelectronics , cmos , amplifier , noise figure
An oscillator is considered as a mixing circuit where the voltage of the oscillator is the local oscillator voltage. A sinusoidal perturbation is applied to the oscillator, exciting current and voltage components at frequencies equivalent to signal, intermediate and image frequencies in a normal mixing circuit. The relationship between the components can be described by three linear equations whose determinant is zero for a d.c. perturbation and for perturbations having the oscillator frequency. By means of the three linear equations the stability, mixing, modulation and demodulation of an oscillator are treated (Section 2). The stability conditions are shown to be the same as those derived by Kurokawa in another way (Section 3). Perturbations of a Van der Pol oscillator are investigated in detail. It is shown that the oscillator obtains a high dynamic Q at small oscillator voltages, and that the sensitivity of a self‐detecting oscillator to load perturbations is independent of the oscillator voltage (Section 4). The signal‐to‐noise ratio of a perturbed oscillator is considered and the conditions for the highest signal‐to‐noise ratio are given (Section 5). Finally, some of the difficulties encountered in making perturbed oscillators for microwave spectrometers are mentioned (Section 6).