Semi-analytical formulation for the analysis and reduction of injection-pulling in front-end oscillators

Injection pulling by interference signals is an undesired phenomenon in front-end oscillators, which causes a shift of the oscillation frequency and degrades the output spectrum. This paper presents a semi-analytical formulation for the insightful analysis of injection-pulling phenomena in the presence of a modulated carrier or chirp signal. The formulation enables an efficient analysis of interference problems difficult to simulate with harmonic balance or standard envelope transient. It allows the modification of the original design in order to reduce the injection pulling to the desired levels. The techniques have been applied to an oscillator at 6 GHz.