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Recently, X-parameters have been introduced to model active device nonlinear behavior. In addition to providing a measurement-based tool to numerically predict nonlinear device behavior in computer-aided design, they can also provide the designer of nonlinear circuits an analytical design tool. Exploiting this design tool aspect, this work presents an application that combines the nonlinear vector network analyzer PNA-X and a passive tuner to extract a transistor load-independent X-parameter model, focused around targeted circuit impedances for optimal performance. Furthermore, an experimental search algorithm, based on X-parameters analytical computations and developed by Peláez-Pérez , has been used and experimentally validated in this paper, aimed to speed up the characterization and design process, minimizing the number of load–pull measurements necessary to provide an accurate transistor X-parameter model for use in analytical and/or numerical circuit design. [ABSTRACT FROM PUBLISHER]

In this paper, an extended version of the continuous class-F^-1 mode power amplifier (PA) design approach is presented. A new formulation describing the current waveform in terms of just two additional parameters, while maintaining a constant half-wave rectified sinusoidal voltage waveform, allows multiple solutions of fundamental and second-harmonic impedances that provide optimum performance to be computed. By varying only the imaginary parts of fundamental and second-harmonic impedances, it is shown that output performance in terms of power and efficiency is maintained constant and equal to that achievable from the standard class-F^-1. Indeed, when presenting resistive second-harmonic impedances, it will be demonstrated that the fundamental load can be adjusted to maintain satisfactory output performances greater than a certain predetermined target value. The measurements, conducted on a GaAs pHEMT device at 1 GHz, show a good agreement with the theoretical analysis, revealing drain efficiencies greater than 70% for a very large range of load solutions, which can translate to an ability to accommodate reactive impedance variations with frequency when designing broadband PAs. [ABSTRACT FROM PUBLISHER]

The extended continuous class-F mode RF power amplifier (PA) is presented for the first time. The introduction and experimental validation of this novel PA mode demonstrates a new design space over a wide band of frequencies. This paper will show that high output power and drain efficiency, equivalent to the class-F mode, can be maintained by varying the reactive components of fundamental and second harmonic impedances in accordance with the new formulation of the voltage waveform. Additionally it will be shown that, by varying both phase and magnitude of the fundamental and second harmonic impedances, a yet wider design space can be achieved, where the efficiency is maintained at a level greater than a certain target value. For the validation of this new theory, an experimental investigation was carried out on GaAs pseudomorphic HEMT devices and demonstrates that high output power and drain efficiency between 75%–83% can be achieved over a wide range of fundamental and second harmonic loads. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on the effective utilization of large-signal measurement data in the nonlinear computer-aided design (CAD) process. To achieve this goal two distinctive, yet mutually complementary, approaches have been integrated. Measured nonlinear data was, in the first instance, directly integrated into a nonlinear CAD simulator, and in the second instance, utilized for a direct extraction of behavioral model parameters. The formulation of the developed model is based on the polyharmonic distortion approach. The combination of both the direct utilization of nonlinear data and the subsequent model generation into an integrated nonlinear design procedure offers rapid, yet reliable, deployment of the CAD-based design environment for complex large-signal simulations. [ABSTRACT FROM AUTHOR]

This paper describes how dc-radio-frequency (RF) dispersion manifests itself in AIGaN/GaN heterojunction field-effect transistors when the devices are driven into different RF load impedances. The localized nature of the dispersion in the I-V plane, which is confined to the "knee" region, is observed in both RF waveform and pulsed I-V measurements. The effect is fully reproduced using 2-D physical modeling. The difference in dispersive behaviors has been attributed to the geometry of a trap-induced virtual-gate region and the resulting carrier velocity saturation being overcome by punchthrough effects under high electric fields. [ABSTRACT FROM AUTHOR]