PROJECT TITLE :

Generalized Stability Criteria for Power Amplifiers Under Mismatch Effects

ABSTRACT:

Potential instability of power amplifiers (PAs) beneath mismatch effects is analyzed, with stress on the convenience and generality of application of the stability criteria. The methodology is based on the analysis of a big-signal version of the $mu$ factor, considering mismatch effects in the fundamental frequency and 3 relevant sidebands: the baseband, the lower sideband and also the higher sideband. This requires an outer-tier scattering-kind conversion matrix of order 3 $times$ 3 to be obtained, with the remainder of sideband equations acting as an inner tier. It's taken into account that the circuit behaves nonlinearly with respect to the termination at the basic frequency. The thought of three sidebands can enable the prediction of the 2 major forms of enormous-signal instability: incommensurable oscillations and frequency divisions by 2. The analysis is preceded by an analysis of the circuit own stability properties (proviso) under open and short circuit terminations at the sidebands, for all possible values of the termination at the elemental frequency. 3 totally different $mu$ factors can be defined between any 2 ports of the scattering matrix. The analysis of the relationships between these factors and their continuity properties will permit the derivation of a single number able to characterize the PA potential instability for each basic-frequency termination. Results have been exhaustively validated with independent circuit-level simulations primarily based on pole-zero identification and with measurements, employing a variable output load and loading the PA with an antenna.