We propose a definition of the efficiency bandwidth for a power amplifier (PA) using a modulated signal as the signal bandwidth at which the amplifier efficiency has dropped to a level of 90% of the maximum efficiency at small bandwidth. We introduce a Monte Carlo method to calculate the efficiency bandwidth for some popular PA architectures. The method assumes a given modulated signal at the load. From this load signal the wave forms at the drains of the transistors are derived and the energy dissipation in the transistors can be calculated. Using idealized transistors with no output capacitance the maximum realizable efficiency bandwidth of an asymmetrical Doherty amplifier is 60%, which is much larger than that of an outphasing amplifier, which is 14%. More realistic transistors that include output capacitances, need a matching circuit with a high Q-value which decreases the efficiency bandwidth. Using output capacitance values typical for LDMOS transistors, the asymmetrical Doherty amplifier shows an efficiency bandwidth of about 400 MHz for a signal centered at 1 GHz. For a signal at 2 GHz the efficiency bandwidth is found to be 520 MHz. Due to the fixed values of the output capacitances the efficiency bandwidth does not scale with frequency.

In this paper, the basic quadratic form of the poly-harmonic distortion model is first presented and this is then extended to provide a new, modified quadratic poly-harmonic distortion model. Comparisons between the X-parameter model, the basic quadratic poly-harmonic distortion model, and the modified version are provided. Both simulation and experimental test results show that the new modified model provides significant improvements in accuracy, not only for the fundamental frequency, but also for DC. Work on the optimization of the model is also presented, providing further improvements in both the model extraction time and the file size.

This paper presents a new macro modeling methodology for solid-state power amplifiers (SSPAs) and packaged transistors used in communication systems. The model topology is based on the principle of harmonic superposition recently introduced by Agilent Technologies' X-parametersTM combined with dynamic Volterra theory. The resulting multi-harmonic bilateral model takes into account the coupling effects of both short- and long-term memory in SSPAs. In this work, the behavioral model was developed from time-domain load pull and used to simulate the amplifier's response to a 16-QAM signal with specific regards to ACPR and IM3.