3 results for Parker, Anthony Edward

  • The random component of mixer-based nonlinear vector network analyzer measurement uncertainty

    Blockley, Peter Stuart; Scott, Jonathan B.; Gunyan, Daniel; Parker, Anthony Edward (2007)

    Journal article
    University of Waikato

    The uncertainty, due to random noise, of the measurements made with a mixer-based nonlinear vector network analyzer are analyzed. An approximate covariance matrix corresponding to the measurements is derived that can be used for fitting models and maximizing the dynamic range in the measurement setup. The validity of the approximation is verified with measurements.

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  • Noise considerations when determining phase of large-signal microwave measurements

    Blockley, Peter Stuart; Scott, Jonathan B.; Gunyan, Daniel; Parker, Anthony Edward (2006)

    Journal article
    University of Waikato

    Advances in microwave instrumentation now make it feasible to accurately measure not only the magnitude spectrum, but also the phase spectrum of wide-bandwidth signals. In a practical measurement, the spectrum is measured over a finite window of time. The phase spectrum is related to the position of this window, causing the spectrum to differ between measurements of an identical waveform. It is difficult to compare multiple measurements with different window positions or to incorporate them into a model. Several methods have been proposed for determining the phase spectrum such that multiple measurements can be effectively compared and utilized in models. The methods are reviewed in terms of the information required to determine the phase and compared in terms of their robustness in the presence of measurement noise.

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  • Performance and applications of Gallium-Nitride Monolithic Microwave Integrated Circuits (GaN MMICs)

    Scott, Jonathan B.; Parker, Anthony Edward (2007-12)

    Conference item
    University of Waikato

    The evolution of wide-bandgap semiconductor transistor technology is placed in historical context with other active device technologies. The relative rapidity of GaN transistor development is noted and is attributed to the great parallel activity in the lighting sector and the historical experience and business model from the III-V compound semiconductor sector. The physical performance expectations for wide-bandgap technologies such as Gallium-Nitride Field-E®ect Transistors (GaN FETs) are reviewed. We present some device characteristics. Challenges met in characterising, and prospects for modeling GaN FETs are described. Reliability is identified as the final remaining hurdle facing would-be foundries. Evolutionary and unsurprising applications as well as novel and revolutionary applications are suggested. Novel applications include wholly monolithic switchmode power supplies, simplified tools for ablation and diathermy in tissue, and very wide dynamic range circuits for audio or low phase noise signal generation. We conclude that now is the time to embark on circuit design of MMICs in wide-bandgap technology. The potential for fabless design groups to capitalise upon design IP without strong geopraphic advantage is noted.

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