Power Amplifiers´ Model Assessment and Memory Effects Intensity Quantification Using Memoryless Post-Compensation Technique

A novel approach for power amplifiers static nonlinearity characterization in the presence of memory effects is presented. A subsampling technique is used to reduce the bandwidth of the test signal without changing the waveform characteristics. This cancels the memory effects of the amplifier without affecting its static behavior. Memoryless AM/AM and AM/PM characteristics are measured as a function of the carrier frequency. This points out the contribution of the frequency dependency of the amplifier´s static nonlinearity to its behavior under wideband signal drive. A memoryless post-compensation technique is then introduced to accurately assess the performance of several behavioral models. In fact, it is demonstrated that direct comparison of the measured output of the device-under-test with the estimated output does not provide reliable assessment of the model performance. Conversely, memoryless post-compensation efficiently differentiates the performance of these models. To provide a comprehensive approach for model validation and prototype performance evaluation, memory effects intensity metrics are introduced. These metrics are applied to evaluate the memory effects present in a 300-W peak power Doherty amplifier driven by various multicarrier wideband code division multiple access signals.