Large-signal stability of symmetric multi-branch power amplifiers exploiting Floquet analysis

The paper presents a comprehensive analysis of the large-signal stability of symmetric multi-branch power amplifiers through the application of Floquet theory implemented directly in the frequency domain. The generality of the approach allows to gain a global assessment of the amplifier stability, without resorting to specific approaches based on layout symmetry nor to the implementation of additional analyses with properly placed ad hoc generators. The spurious frequency oscillations and the most critical circuit locations are identified by a novel, computationally efficient and accurate harmonic-balance evaluation of the Floquet exponents and of their associated eigenvectors. Smalland large-signal stability analyses are validated against conventional criteria and time-domain simulations, respectively. Based on this analysis, significant differences between small-signal and large-signal stability conditions for intrinsically nonlinear stages are found, thus driving the design towards optimized stabilization solutions.