A method for multi-mode stability analysis of power amplifier

A method for multi-mode stability analysis of power amplifier is presented which does not demand strict circuit symmetry. Transformation from n-port signals to n-mode signals is used to provide the oscillating signal's “mode” information which allows the circuit designer to find the instability source and to adopt suitable methods for circuit stabilization. The proposed method has been applied to a four-branch combining power amplifier circuit to verify its effectiveness.