A measurement-based quasi-static nonlinear field-effect transistor (FET) model relying on an artificial neural network (ANN) approach and using real-time active load-pull (RTALP) measurement data for the model extraction is presented for an SOS-MOSFET. The efficient phase sweeping of the RTALP drastically reduces the number of large-signal measurements needed for the model development and verification while maintaining the same intrinsic voltage coverage as in conventional passive or active load-pull systems. Memory effects associated with the parasitic bipolar junction transistor (BJT) in the SOS-MOSFET are accounted for by using a physical circuit topology together with the simultaneous ANN extraction of: 1) the intrinsic FET current-voltage characteristics; 2) the intrinsic charges of the FET; and 3) the BJT dc characteristics, all from the same modulated large-signal RF data. The verification of the model using load-lines, output power, power efficiency, and load-pull, which is performed using two additional independent RTALP measurements, demonstrates that a reasonably accurate large-signal RF device model accounting for memory effects can be extracted from a single 10.5-ms RTALP measurement with a physically based ANN model. Index Terms-Artificial neural network (ANN), large-signal network analyzer (LSNA), memory effects, MOSFET, parasitic bipolar junction transistor (P-BJT), real-time active load-pull (RTALP).

n the last decades, vector network analyzers (VNA) have been successful for the characterization and modeling of time-invariant RF devices exhibiting mildly nonlinear response using swept continuous wave (CW) excitations. As the demand on wireless communication has grown, new modulation schemes such as WiMAX and long-term evolution (LTE) have been introduced that require higher peak-to-average-power ratio (PAPR) in the time-domain and wider bandwidth in the frequency domain. These modulated signals have forced many components, especially power amplifiers, to operate in a harsher nonlinear regime. Modern power amplifiers must therefore handle modulated signals with higher PAPR while keeping high average power. To assist with the device modeling and the amplifier design process, improved measurement systems are required which characterize their nonlinear response under realistic operating conditions.Since the first work reported by Lott in 1989 [2], many large-signal VNAs (LSNAs) or nonlinear VNAs (NVNAs) have been developed to characterize, under calibrated conditions, nonlinear devices excited by CW or periodically modulated RF signals. The LSNA and NVNA measure the absolute amplitude and relative phase of the harmonics of voltage and current waves at the measurement reference planes. Among the various architectures, the most popular are the sampler-based LSNAs and the mixer-based NVNAs. The

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