Behavioural model analysis of active harmonic load-pull measurements

In this thesis, an investigation of the use of the poly-harmonic distortion model and related techniques is conducted, and applied to model fundamental and harmonic load-pull. Contained within the thesis is a detailed review of the development of the poly-harmonic distortion model and related methods. This thesis shows that although the poly-harmonic distortion model improves on the prediction of fundamental load-pull, over Hot-S-Parameters it still has a limited range of application. To address this observation, higher order models have been investigated along with Fourier methods allowing rapid extraction of the behavioral models. These methods allow conclusions to be drawn on the accuracy of the extracted models, by the direct observation of the magnitudes of the model coefficients. The thesis is concluded with the presentation of the results from third party, using a model extracted using the methods discussed in this thesis. The Model is of a 0.5W GaAs pHEMT at 9 GHz and is used within the design of a Class-J MMIC amplifier

Behavioural model analysis of active harmonic load-pull measurements

In this thesis, an investigation of the use of the poly-harmonic distortion model and related techniques is conducted, and applied to model fundamental and harmonic load-pull. Contained within the thesis is a detailed review of the development of the poly-harmonic distortion model and related methods. This thesis shows that although the poly-harmonic distortion model improves on the prediction of fundamental load-pull, over Hot-S-Parameters it still has a limited range of application. To address this observation, higher order models have been investigated along with Fourier methods allowing rapid extraction of the behavioral models. These methods allow conclusions to be drawn on the accuracy of the extracted models, by the direct observation of the magnitudes of the model coefficients. The thesis is concluded with the presentation of the results from third party, using a model extracted using the methods discussed in this thesis. The Model is of a 0.5W GaAs pHEMT at 9 GHz and is used within the design of a Class-J MMIC amplifier.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Large-signal oscillator design procedure utilizing analytical x-parameters closed-form expressions

New analytical behavioral model formulations based on the polyharmonic distortion (PHD) model have been successfully used to describe the nonlinear behavior of transistors and circuits. In this paper, the PHD model and its associated analytical X -parameters formulation will be utilized to provide an analytical design procedure for use in nonlinear microwave circuit design. For RF oscillator design, the negative-resistance method based on the analytical manipulation of scattering parameters is very popular due to its high rate of success in oscillation frequency prediction. However, it cannot be used to accurately predict the oscillator performance because it is based on linear parameters. To overcome this limitation, new analytical expressions based on large-signal X-parameters have been developed for use in transistor-based oscillator circuit design. The robustness of this new approach has been validated by designing and manufacturing a 5-GHz microwave oscillator

An accurate calibrate-able multiharmonic active load-pull system based on the envelope load-pull concept

After calibration, since the systematic imperfections of the envelop load-pull (ELP) components were now fully accounted for, the user is able to rapidly set accurate terminations with full Smith chart coverage. This functionality has been achieved by optimizing the hardware configuration of the envelop load-pull concept. Development of a system whose systematic errors could be described by a magnitude invariant error flow model was critical. As a consequence, a robust calibration mechanism, that is analogous to the one-port error correction of a vector network analyzer, was exploited and comprehensively verified. After calibration, since the systematic imperfections of the ELP components were now fully accounted for, the user is able to set accurately terminations with full Smith chart coverage. Finally, measurements on commercially available transistor devices are presented that verify the rapid nature, accuracy, flexibility, reliability, and ease of calibration of the multiharmonic load-pull system

Behavioral model analysis of active harmonic load-pull measurements

This paper outlines the formulation of a mixing based behavioral model, capable of capturing the nonlinear response of microwave transistors to fundamental and harmonic load pull effects for use in Computer Aided Design tools. The key to the model formulation was the experimental identification of the dominating mixing terms. The model is able to accurately compute the voltage and current waveforms present at a Transistors Terminals. The formulation lends itself to economical use of measured data, reducing data storage required within the CAD environment. In this paper the modeling approach has been demonstrated on a 10 × 75 μm GaAs HEMT operating at 9 GHz

Behavioral model analysis using simultaneous active fundamental load-pull and harmonic source-pull measurements at X-band

Recently there has been a renewed interest in improving power amplifier performance via input waveform engineering. In order to support this development it is important that non-linear behavioral device models can accurately describe and fully account for the high levels of input harmonic signal injection necessary. The work presented in this paper introduces an adapted mixing model formulation, which was used to extract input second harmonic model coefficients from a set of simultaneous active fundamental load-pull and harmonic source-pull measurements at 9 GHz. It was observed that a fourth order model was sufficient to capture the response of the scattered travelling b2,1 and b2,2 waves to a confidence of 99.46% and 97.62% respectively of the measured data. Hereafter the behavioral model was used to accurately generate the full fundamental output impedance space and the respective port current and voltage waveforms within a CAD environment

Experimental verification of analytical design equations based on X-parameters® for predicting role of series feedback

Recently, new behavioral model formulations have been introduced to describe transistor non-linear behavior. In addition to providing an alternative approach to modeling nonlinear behavior in CAD tools based directly on measured data, they also provide for the possibility of extending analytical circuit analysis to the domain of non-linear circuits. An important example would be an analytical means to compute the effect of adding a network series connection. Such a formulation has been derived and in this paper experimentally validated. This new formulation is very interesting since it provides the key component required for developing analytical circuit design procedures for feedback amplifiers and oscillators