The Experts below are selected from a list of 18462 Experts worldwide ranked by ideXlab platform
Robert J. Marks - One of the best experts on this subject based on the ideXlab platform.
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dynamic online learning applied to fast switched stub Impedance tuner for frequency and Load Impedance agility in radar applications
2020 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2020Co-Authors: Caleb Calabrese, Charles Baylis, Angelique Dockendorf, Austin Egbert, Robert J. MarksAbstract:Switched-stub tuner topologies show promise for use in real-time tuning of high-power amplifiers in radar transmitter arrays. High-power switches can be used to expose or remove different tuning stubs from a series line in real time to adjust power-amplifier Load Impedance following changes in operating frequency or array scan angle. Dynamic online learning can be applied to enhance optimization of the amplifiers by updating models for tuner performance in realtime. This minimizes experimental queries needed to reoptimize on the fly as the system adjusts its operating frequency or scan angle. Measurement results are presented to optimize a six-stub tuner in a 2–4 GHz window with varying antenna Impedances from a software-defined radio platform. Results show significant time savings can be achieved by applying dynamic learning.
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Bias Smith Tube Optimization of Drain Voltage and Load Reflection Coefficient to Maximize Power-Added Efficiency Under ACPR Constraints for Radar Power Amplifiers
IEEE Transactions on Aerospace and Electronic Systems, 2019Co-Authors: Matthew Fellows, Charles Baylis, Joseph Barkate, Lawrence Cohen, Alexander Tsatsoulas, Sarvin Rezayat, Lucilia Lamers, Robert J. MarksAbstract:Reconfigurable transmitter power amplifiers will be necessary in future cognitive radar systems to allow adjustment in operating frequency, spectral output, and other desired operating characteristics while maintaining performance. Circuit optimization algorithms for tuning the amplifier Load Impedance and bias voltage in real time should maximize power-added efficiency while limiting the adjacent-channel power ratio (ACPR) in order to obtain spectral compliance. This paper presents a fast vector-based three-dimensional optimization for simultaneous bias adjustment and Impedance matching for these goals using the bias Smith tube as the optimization space. Simulation and measurement results are presented for this optimization algorithm, and correspondence between the results is examined for several different starting locations in the bias Smith tube. This algorithm will allow simultaneous optimization of bias voltage and Load Impedance in real time in order to meet changing requirements.
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fast simultaneous optimization of power amplifier input power and Load Impedance for power added efficiency and adjacent channel power ratio using the power smith tube
IEEE Transactions on Aerospace and Electronic Systems, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Jennifer Barlow, Charles Baylis, Matthew Flachsbart, Zachary Hays, Lawrence Cohen, Robert J. MarksAbstract:Reconfigurable adaptive amplifiers are expected to be a critical component of future adaptive and cognitive radar transmitters. This paper details an algorithm to simultaneously optimize input power and Load reflection coefficient of a power amplifier device to obtain the largest power-added efficiency (PAE) possible under a predefined constraint on adjacent-channel power ratio (ACPR). The vector-based search relies on estimation of the PAE and ACPR gradients in the three-dimensional power Smith tube. Accurate convergence to the optimum Impedance in the Smith chart is demonstrated in simulation and measurement search experiments requiring between 20 and 60 experimental queries. This paper presents a fast search to jointly optimize the input power level and Load Impedance. This method is feasible for future implementation in real-time reconfigurable power amplifiers.
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Designing Power Amplifiers for Spectral Compliance Using Spectral Mask Load-Pull Measurements
2016Co-Authors: Matthew Fellows, Jennifer Barlow, Charles Baylis, Joseph Barkate, Robert J. MarksAbstract:Abstract — This paper demonstrates power amplifier design using Load-pull measurements to determine spectral mask compliance as a function of Load Impedance. In most cases demonstrated in the open literature, the spectral spreading of the device is indirectly assessed by a metric such as the adjacent-channel power ratio or third-order intermodulation product. In the present paper, a spectral mask compliance metric is introduced that is less than or equal to zero for compliant spectra and positive for non-compliant spectra. The paper first examines the Load-pull measurement for the spectral mask compliance metric, including the use of averaging to smooth the contours. Direct, dual-objective design of power amplifiers for spectral mask compliance and efficiency is then demonstrated by choosing the Load Impedance that provides the highest measured power-added efficiency while maintaining spectral compliance. With the device terminated in the chosen optimum Impedance, measurement of the output spectrum and comparison with a spectral mask are performed to demonstrate spectral compliance at the selected design Impedance. Index Terms — power amplifiers, Impedance, radio spectrum management, energy efficiency, linearity. I
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fast momentum aided optimization of transmitter amplifier Load Impedance and input power for cognitive radio using the power smith tube
Radio and Wireless Symposium, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Charles Baylis, Matthew Flachsbart, Lawrence Cohen, Alexander Tsatsoulas, Robert J. MarksAbstract:A fast search including momentum is used to quickly and simultaneously optimize power-amplifier Load Impedance and input power for the highest power-added efficiency while maintaining adjacent-channel power ratio within compliance limits. This search makes use of the recently developed Power Smith Tube, and is expected to be useful in real-time reconfigurable communications and radar transmitters, as well as for fast computer and measurement aided design of power amplifiers. Simulation and measurement results are shown to demonstrate the improved accuracy provided by adding momentum to the search.
Byungcho Choi - One of the best experts on this subject based on the ideXlab platform.
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a Load Impedance specification of dc power systems for desired dc link dynamics and reduced conservativeness
IEEE Transactions on Power Electronics, 2019Co-Authors: Syam Kumar Pidaparthy, Byungcho ChoiAbstract:This paper proposes a new Load Impedance specification for multistage dc power conversion systems. The proposed specification avoids drawbacks of the existing specifications, such as the lack of explicit connections to the dc-link dynamics and the unnecessary conservativeness. The new specification offers a direct command/supervision of the frequency- and time-domain dynamics of the intermediate dc link, while being less conservative than the existing specifications. This paper also presents procedures for redesigning ill-conditioned Load Impedances to comply with the specification. The validity and utility of the proposed specification are demonstrated using an experimental two-stage dc power conversion system.
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a Load Impedance specification of dc power systems for desired dc link dynamics and reduced conservativeness
Workshop on Control and Modeling for Power Electronics, 2017Co-Authors: Syam Kumar Pidaparthy, Byungcho ChoiAbstract:This paper proposes a new Load Impedance specification for multi-stage dc power conversion systems. The proposed specification avoids drawbacks of the existing specifications, such as the lack of explicit connections to the dc link dynamics and unnecessary conservativeness. The proposed specification offers a direct command/supervision of the frequency- and time-domain dynamics of the intermediate dc link, while being less conservative than the existing specifications. This paper also presents procedures of redesigning ill-conditioned Load Impedances to comply with the specification. The validity and utility of the proposed specification are demonstrated using an illustrative example.
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A method of defining the Load Impedance specification for a stable distributed power system
IEEE Transactions on Power Electronics, 1995Co-Authors: C.m. Wildrick, F C Lee, Bo-hyung Cho, Byungcho ChoiAbstract:By applying the loop gain analysis technique, a forbidden region for the polar plot of the ratio of Impedances at the interface between two cascaded power subsystems is determined. A method of transforming the forbidden region into a Load Impedance specification for a given source Impedance is developed. The method assures system stability and minimal performance degradation of the distributed power system, while allowing Impedance overlap at the interface. >
Sangwook Nam - One of the best experts on this subject based on the ideXlab platform.
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Determination of the Impedance Parameters of Antennas and the Maximum Power Transfer Efficiency of Wireless Power Transfer
IEEE Transactions on Antennas and Propagation, 2019Co-Authors: Yoon Kim, Sangwook NamAbstract:In this paper, we derive formulas that calculate the Impedance parameters (Z-parameters) of multiple antennas near objects to analyze wireless power transfer. Furthermore, we propose a method to calculate the Impedance parameters of antennas, the maximum power transfer efficiency, and the optimum Load Impedance of a wireless power transfer system using equivalent current that generate the same electromagnetic field as that generated by an antenna in transmitting mode.
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fundamental aspects of near field coupling small antennas for wireless power transfer
IEEE Transactions on Antennas and Propagation, 2010Co-Authors: Jaechun Lee, Sangwook NamAbstract:A physical limitation on the power transfer efficiency between two electrically small antennas in the near-field range is presented. By using a Z-parameter which describes the interaction between two antennas for spherical modes in connection with antenna parameters, the maximum power transfer efficiency and the optimum Load Impedance are shown as functions of the distance between two antennas, the radiation efficiency and the input Impedance of the isolated antenna. The theory is verified by a simulation with a small helical antenna, which generates and modes, simultaneously.
Charles Baylis - One of the best experts on this subject based on the ideXlab platform.
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dynamic online learning applied to fast switched stub Impedance tuner for frequency and Load Impedance agility in radar applications
2020 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), 2020Co-Authors: Caleb Calabrese, Charles Baylis, Angelique Dockendorf, Austin Egbert, Robert J. MarksAbstract:Switched-stub tuner topologies show promise for use in real-time tuning of high-power amplifiers in radar transmitter arrays. High-power switches can be used to expose or remove different tuning stubs from a series line in real time to adjust power-amplifier Load Impedance following changes in operating frequency or array scan angle. Dynamic online learning can be applied to enhance optimization of the amplifiers by updating models for tuner performance in realtime. This minimizes experimental queries needed to reoptimize on the fly as the system adjusts its operating frequency or scan angle. Measurement results are presented to optimize a six-stub tuner in a 2–4 GHz window with varying antenna Impedances from a software-defined radio platform. Results show significant time savings can be achieved by applying dynamic learning.
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Bias Smith Tube Optimization of Drain Voltage and Load Reflection Coefficient to Maximize Power-Added Efficiency Under ACPR Constraints for Radar Power Amplifiers
IEEE Transactions on Aerospace and Electronic Systems, 2019Co-Authors: Matthew Fellows, Charles Baylis, Joseph Barkate, Lawrence Cohen, Alexander Tsatsoulas, Sarvin Rezayat, Lucilia Lamers, Robert J. MarksAbstract:Reconfigurable transmitter power amplifiers will be necessary in future cognitive radar systems to allow adjustment in operating frequency, spectral output, and other desired operating characteristics while maintaining performance. Circuit optimization algorithms for tuning the amplifier Load Impedance and bias voltage in real time should maximize power-added efficiency while limiting the adjacent-channel power ratio (ACPR) in order to obtain spectral compliance. This paper presents a fast vector-based three-dimensional optimization for simultaneous bias adjustment and Impedance matching for these goals using the bias Smith tube as the optimization space. Simulation and measurement results are presented for this optimization algorithm, and correspondence between the results is examined for several different starting locations in the bias Smith tube. This algorithm will allow simultaneous optimization of bias voltage and Load Impedance in real time in order to meet changing requirements.
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fast simultaneous optimization of power amplifier input power and Load Impedance for power added efficiency and adjacent channel power ratio using the power smith tube
IEEE Transactions on Aerospace and Electronic Systems, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Jennifer Barlow, Charles Baylis, Matthew Flachsbart, Zachary Hays, Lawrence Cohen, Robert J. MarksAbstract:Reconfigurable adaptive amplifiers are expected to be a critical component of future adaptive and cognitive radar transmitters. This paper details an algorithm to simultaneously optimize input power and Load reflection coefficient of a power amplifier device to obtain the largest power-added efficiency (PAE) possible under a predefined constraint on adjacent-channel power ratio (ACPR). The vector-based search relies on estimation of the PAE and ACPR gradients in the three-dimensional power Smith tube. Accurate convergence to the optimum Impedance in the Smith chart is demonstrated in simulation and measurement search experiments requiring between 20 and 60 experimental queries. This paper presents a fast search to jointly optimize the input power level and Load Impedance. This method is feasible for future implementation in real-time reconfigurable power amplifiers.
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Designing Power Amplifiers for Spectral Compliance Using Spectral Mask Load-Pull Measurements
2016Co-Authors: Matthew Fellows, Jennifer Barlow, Charles Baylis, Joseph Barkate, Robert J. MarksAbstract:Abstract — This paper demonstrates power amplifier design using Load-pull measurements to determine spectral mask compliance as a function of Load Impedance. In most cases demonstrated in the open literature, the spectral spreading of the device is indirectly assessed by a metric such as the adjacent-channel power ratio or third-order intermodulation product. In the present paper, a spectral mask compliance metric is introduced that is less than or equal to zero for compliant spectra and positive for non-compliant spectra. The paper first examines the Load-pull measurement for the spectral mask compliance metric, including the use of averaging to smooth the contours. Direct, dual-objective design of power amplifiers for spectral mask compliance and efficiency is then demonstrated by choosing the Load Impedance that provides the highest measured power-added efficiency while maintaining spectral compliance. With the device terminated in the chosen optimum Impedance, measurement of the output spectrum and comparison with a spectral mask are performed to demonstrate spectral compliance at the selected design Impedance. Index Terms — power amplifiers, Impedance, radio spectrum management, energy efficiency, linearity. I
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fast momentum aided optimization of transmitter amplifier Load Impedance and input power for cognitive radio using the power smith tube
Radio and Wireless Symposium, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Charles Baylis, Matthew Flachsbart, Lawrence Cohen, Alexander Tsatsoulas, Robert J. MarksAbstract:A fast search including momentum is used to quickly and simultaneously optimize power-amplifier Load Impedance and input power for the highest power-added efficiency while maintaining adjacent-channel power ratio within compliance limits. This search makes use of the recently developed Power Smith Tube, and is expected to be useful in real-time reconfigurable communications and radar transmitters, as well as for fast computer and measurement aided design of power amplifiers. Simulation and measurement results are shown to demonstrate the improved accuracy provided by adding momentum to the search.
Matthew Fellows - One of the best experts on this subject based on the ideXlab platform.
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Bias Smith Tube Optimization of Drain Voltage and Load Reflection Coefficient to Maximize Power-Added Efficiency Under ACPR Constraints for Radar Power Amplifiers
IEEE Transactions on Aerospace and Electronic Systems, 2019Co-Authors: Matthew Fellows, Charles Baylis, Joseph Barkate, Lawrence Cohen, Alexander Tsatsoulas, Sarvin Rezayat, Lucilia Lamers, Robert J. MarksAbstract:Reconfigurable transmitter power amplifiers will be necessary in future cognitive radar systems to allow adjustment in operating frequency, spectral output, and other desired operating characteristics while maintaining performance. Circuit optimization algorithms for tuning the amplifier Load Impedance and bias voltage in real time should maximize power-added efficiency while limiting the adjacent-channel power ratio (ACPR) in order to obtain spectral compliance. This paper presents a fast vector-based three-dimensional optimization for simultaneous bias adjustment and Impedance matching for these goals using the bias Smith tube as the optimization space. Simulation and measurement results are presented for this optimization algorithm, and correspondence between the results is examined for several different starting locations in the bias Smith tube. This algorithm will allow simultaneous optimization of bias voltage and Load Impedance in real time in order to meet changing requirements.
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fast simultaneous optimization of power amplifier input power and Load Impedance for power added efficiency and adjacent channel power ratio using the power smith tube
IEEE Transactions on Aerospace and Electronic Systems, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Jennifer Barlow, Charles Baylis, Matthew Flachsbart, Zachary Hays, Lawrence Cohen, Robert J. MarksAbstract:Reconfigurable adaptive amplifiers are expected to be a critical component of future adaptive and cognitive radar transmitters. This paper details an algorithm to simultaneously optimize input power and Load reflection coefficient of a power amplifier device to obtain the largest power-added efficiency (PAE) possible under a predefined constraint on adjacent-channel power ratio (ACPR). The vector-based search relies on estimation of the PAE and ACPR gradients in the three-dimensional power Smith tube. Accurate convergence to the optimum Impedance in the Smith chart is demonstrated in simulation and measurement search experiments requiring between 20 and 60 experimental queries. This paper presents a fast search to jointly optimize the input power level and Load Impedance. This method is feasible for future implementation in real-time reconfigurable power amplifiers.
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Designing Power Amplifiers for Spectral Compliance Using Spectral Mask Load-Pull Measurements
2016Co-Authors: Matthew Fellows, Jennifer Barlow, Charles Baylis, Joseph Barkate, Robert J. MarksAbstract:Abstract — This paper demonstrates power amplifier design using Load-pull measurements to determine spectral mask compliance as a function of Load Impedance. In most cases demonstrated in the open literature, the spectral spreading of the device is indirectly assessed by a metric such as the adjacent-channel power ratio or third-order intermodulation product. In the present paper, a spectral mask compliance metric is introduced that is less than or equal to zero for compliant spectra and positive for non-compliant spectra. The paper first examines the Load-pull measurement for the spectral mask compliance metric, including the use of averaging to smooth the contours. Direct, dual-objective design of power amplifiers for spectral mask compliance and efficiency is then demonstrated by choosing the Load Impedance that provides the highest measured power-added efficiency while maintaining spectral compliance. With the device terminated in the chosen optimum Impedance, measurement of the output spectrum and comparison with a spectral mask are performed to demonstrate spectral compliance at the selected design Impedance. Index Terms — power amplifiers, Impedance, radio spectrum management, energy efficiency, linearity. I
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fast momentum aided optimization of transmitter amplifier Load Impedance and input power for cognitive radio using the power smith tube
Radio and Wireless Symposium, 2016Co-Authors: Joseph Barkate, Matthew Fellows, Charles Baylis, Matthew Flachsbart, Lawrence Cohen, Alexander Tsatsoulas, Robert J. MarksAbstract:A fast search including momentum is used to quickly and simultaneously optimize power-amplifier Load Impedance and input power for the highest power-added efficiency while maintaining adjacent-channel power ratio within compliance limits. This search makes use of the recently developed Power Smith Tube, and is expected to be useful in real-time reconfigurable communications and radar transmitters, as well as for fast computer and measurement aided design of power amplifiers. Simulation and measurement results are shown to demonstrate the improved accuracy provided by adding momentum to the search.
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the bias smith tube simultaneous optimization of bias voltage and Load Impedance in power amplifier design
Radio and Wireless Symposium, 2016Co-Authors: Matthew Fellows, Jennifer Barlow, Charles Baylis, Joseph Barkate, Lawrence Cohen, Alexander Tsatsoulas, Sarvin Rezayat, Robert J. MarksAbstract:Multiple factors must be considered in power-amplifier design for wireless communications and radar, including bias voltage, input power, and Load Impedance. The Bias Smith Tube is presented as a three-dimensional extension of the Smith Chart with bias voltage as the vertical axis. It allows simultaneous visualization of nonlinear output characteristic behaviors over transistor bias voltage and Load reflection coefficient. Simulated and measured three-dimensional surfaces of constant power-added efficiency (PAE), adjacent channel power ratio (ACPR), and delivered power are shown in the Bias Smith Tube, and a design approach is illustrated that finds the combination of Load Impedance and bias voltage providing maximum PAE under ACPR and/or delivered power constraints.
