Large Signal Analysis, Nonlinear VNA Measurements and Behavioral Model Extraction


Device characterization is required for power amplifier design, and the ideal form of the device data is a large signal model. With a model, the performance can be analyzed for varying drive and impedance conditions, so complex or multi-stage circuits can be designed. A method of formulating a large signal model is to use a measurement-based behavioral approach, popularized by Keysight Technologies' X-Parameter model and AMCAD's EPHD models. These models are extracted from large-signal nonlinear VNA measurements.

Large Signal Analysis (LSA) and Nonlinear VNA (NVNA) Measurements

Also referred to as time-domain analysis and waveform engineering, LSA and NVNA measurements allow the analysis of currents and voltages at the device input and output terminals in order to identify the DUT’s mode of operation. This tool is useful in the study and design of advanced amplifier classes of operation including E, F, J and K and their inverses.

This is accomplished by recording the phase dependency of harmonic content and allows a- and b-waves, voltage and current waveforms, and load lines to be displayed for each measurement state (impedance/power/bias) and can be de-embedded to the device reference plane.

Enhanced PHD (EPHD)

Keysight X-Parameters (PHD) and AMCAD Enhanced PHD (EPHD) Behavioral Models

X-Parameters are the result of polyharmonic distortion methodology (harmonic superposition) which uses harmonic extraction tones to quantify the harmonic nonlinearities of a DUT.

Enhanced PHD (EPHD) is ideal for behavioral modeling of unmatched transistor in which extrapolation of loading conditions may be required beyond those used in the modeling extraction process.

ADS Comparison of Measured and Modeled Performance Parameters

Tour IVCAD Software Suite

IVCAD advanced measurement and modeling software, offered by Maury Microwave and AMCAD Engineering supports multiple load pull techniques including traditional load pull using external instrumentation, VNA-based load pull, active load pull and hybrid load pull. It performs DC-IV and pulsed-IV measurements and incorporates device modeling tools. Its modern visualization capabilities give users a greater ability to view, plot and graph measurement data in an intuitive manner.

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Application Notes and Data Sheets


Multiharmonic Volterra (MHV) Model Dedicated to the Design of Wideband and Highly Efficient GaN Power Amplifiers 5A-061


High Efficiency Doherty Power Amplifier Design using Enhanced Poly-Harmonic Distortion (EPHD) Model 5A-065


Behavioral Power Amplifier Model (MHV) considering Memory Effects dedicated to radar system simulation 5A-066


A multi-harmonic model (MHV) taking into account coupling effects of long- and short-term memory in SSPAs 5A-067


Integrated, Turnkey Modeling & Measurement Systems 5A-068