Time filter

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United Kingdom

Fernandez-Barciela M.,University of Vigo | Pelaez-Perez A.M.,Televes S.A. | Woodington S.,Mesuro Ltd. | Alonso J.I.,Technical University of Madrid | Tasker P.J.,University of Cardiff
IEEE Microwave Magazine | Year: 2014

In the design of most electronic circuits and systems, designers use computer-aided design (CAD) tools to guide the design flow. They exploit the ability of CAD tools to perform algebraic operations to compute/predict circuit and system performance. This is possible because, in most electronic circuits and systems, linear operation can be assumed. The behavior of microwave components, circuits, and systems can, for example, be described in terms of behavioral parameters, such as Z-parameters, Y-parameters, and S-parameters. Transformation from one parameter to another is achieved by simple linear algebraic operations [1]. The performance of more complex circuits can be computed via linear matrix operations using the relevant parameters, i.e., Y-parameters for parallel connections and Z-parameters for series connections. More significantly, performance predictions can also be obtained via linear algebra transformations, i.e., the maximum gain, minimum noise figure, potential instability, etc., along with design insight, i.e., gain circles, noise circles, optimum input/output match requirements, and so on [1], [2]. © 2014 IEEE.

Faraj J.,Verspecht Teyssier DeGroote SAS | Mathias S.,Mesuro Ltd. | Teyssier J.-P.,University of Limoges | Benedikt J.,University of Cardiff | Casbon M.,University of Cardiff
Microwave Journal | Year: 2011

The SWAP X402, a cost-effective sampler-based Nonlinear Vector Network Analyzer (NVNA) product from Verspecht-Teyssier-DeGroote (VTD), has resulted in a very versatile and fast Time Domain Load-Pull setup running with the same level of performances in CW or pulsed mode. The sampler, with extended pulse capabilities that is compatible in terms of hardware and software with an active load-pull system, contains four independent and synchronized RF sampler-based receivers, whose role is the conversion of the RF signals into intermediate signals. An another system, the VTD NVNA measurement system, is used within pulsed load-pull measurements and as such, the development team at Mesuro has implemented it as the receiver in its current open-loop Active Harmonic Load-Pull solution. The greatly reduced thermal loading on the device enables measurements far beyond the safe CW operating region and under more realistic operating conditions.

Aldoumani A.,University of Cardiff | Williams T.,Mesuro Ltd. | Lees J.,University of Cardiff | Tasker P.J.,University of Cardiff
83rd ARFTG Microwave Measurement Conference: Microwave Measurements for Emerging Technologies, ARFTG 2014 | Year: 2014

This paper presents an alternative approach to improving the vector measurement accuracy, especially near the edge of the Smith Chart, of load-pull measurement systems. Improved measurement accuracy, after vector calibration, is achieved by exploiting the load-pull capability during calibration to minimize the impact of measurement errors on the raw data of the calibration standards before it is utilized in the traditionally implemented LRL/TRL calibration algorithm. This approach eliminates the need to utilize complex optimization algorithms post calibration. The proposed method has been tested and applied to actual measurement data. © 2014 IEEE.

Saini R.S.,University of Cardiff | Bell J.J.,University of Cardiff | Williams T.,Mesuro Ltd. | Lees J.,University of Cardiff | And 2 more authors.
78th ARFTG Microwave Measurement Conference: High Power RF Measurement Techniques, ARFTG 2011 | Year: 2011

This paper demonstrates how the Poly Harmonic Distortion (PHD) modelling framework is effective in its ability to interpolate or extrapolate non-linear measured data and thereby improve the quality and speed of measurement systems. Fundamental interpolation was verified and demonstrated using a 7-coefficient model extracted from a sparse set of fundamental impedances (19 points). It was shown that a relatively low order polynomial was required to capture the second harmonic space. Interpolation accuracy was however increased by including more coefficients. Second harmonic extrapolation was carried out on measured data and shown to be accurate to an average confidence of 99% when 6 model coefficients were extracted on a 0.7 reflection coefficient circle and then used to predict data on a 1.0 reflection coefficient circle. Measurements were carried out using an open loop active load-pull system operating at a fundamental frequency of 9GHz, on a 0.5W 10x75um GaAs PHEMT device. © 2011 IEEE.

Pelaez-Perez A.M.,Technical University of Madrid | Pelaez-Perez A.M.,Mesuro Ltd. | Woodington S.,Alcatel - Lucent | Fernandez-Barciela M.,University of Vigo | And 2 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

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. © 1963-2012 IEEE.

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