Efficient Calculation of Stabilization Parameters in RF Power Amplifiers

• Published in: IEEE transactions on microwave theory and techniques Vol. 68; no. 9; pp. 3686 - 3696
• Main Authors: Mori, Libe, Lizarraga, Ibone, Anakabe, Aitziber, Collantes, Juan-Mari, Armengaud, Vincent, Soubercaze-Pun, Geoffroy
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-09-2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer simulation; Control theory; Harmonic analysis; Harmonic transfer function (HTF); Linear control; Mathematical model; Microwave circuits; nonlinear analysis; Numerical methods; Parameters; Power amplifiers; Stability analysis; Stabilization; Steady-state; system identification; Transfer functions
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2020.3006185

This article proposes an efficient method for the calculation of the stabilization parameters in RF power amplifiers operating in periodic large-signal regimes. Stabilization is achieved by applying the principles of linear control theory for periodic linear time-varying (PLTV) systems. A numerical method is proposed to obtain the harmonic transfer function that represents the system linearized around the large-signal steady state. Then, a feedback analysis is performed to calculate the closed-loop poles of the PLTV system. The proposed approach is demonstrated with two examples. First, a three-stage amplifier that exhibits a low-frequency oscillation for increasing values of input power is correctly stabilized. Next, the stabilization of an unstable design that exhibits an odd-mode parametric oscillation is presented. The results of the proposed technique are compared to those obtained with the conventional parametric stability simulation. These examples serve to illustrate the capability and efficiency of the proposed approach.