Nonlinear stability analysis of a ultra-wide band doubler MMIC

An improved nonlinear stability analysis technique for circuits is presented. This technique is mainly implemented by adding variable terminal impedances and an additional auxiliary perturbation generator into a circuit node. This method can find out the potential oscillation of nonlinear circuits under the terminal unmatched condition. The method has been applied to an ultra-wide band doubler microwave monolithic integrate circuit for detecting the autonomous oscillations of DC regime under the unmatched terminal impedance condition. The simulation is in good agreement with measurements. Finally, the paper shows the measured conversion gain under matched terminal, and the minimum gain is about -4 dB over 3-50 GHz.