Evaluation of RF PA nonlinearities based on cross-correlation between current and output voltage

The estimation of 1 dB compression and third-order intercept points can be obtained after the cross-correlation between dynamic current and output voltage of radio frequency power amplifiers. Estimation is performed using power measures and not power inferred from voltage measures. The underlining theory and a correlator that allows implementing this measurement on-chip are presented. The trade-off between measuring voltage or the actual power is also discussed. It is also shown that different information concerning the output load is obtained when observing the PA´s output voltage and power. Simulation results, obtained with the model of a prototype demonstration chip show that good accuracy can be obtained with relatively simple measurement conditions. These results include the analysis of optimum stimuli amplitudes and the effect of noise in estimation accuracy.