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Displaying 726 - 750 of 1560

Different Dynamic and Static Magnetic Anisotropy in Thin Permalloy Films

July 6, 2003
Author(s)
Radek Lopusnik, John P. Nibarger, Thomas J. Silva, Zbigniew J. Celinski
The values of uniaxial anisotropy Hk in thin polycrystalline Permalloy films measured by static and dynamic methods differ by as much as a factor 1.5. The anisotropy obtained with a pulsed inductive microwave magnetometer in 2.5-100 nm thick Permalloy

High-frequency noise measurements in spin-valve Devices

July 1, 2003
Author(s)
N. A. Stutzke, S. L. Burkett, Stephen E. Russek
High-frequency magnetic noise in magnetoresistive devices being developed for read-sensor and magnetic random access memory applications may present fundamental limitations on the performance of sub-micrometer magnetic devices. High- frequency magnetic

In-situ conductance characterization of Fe/Ag multilayer contacts on GaAs

July 1, 2003
Author(s)
Dustin Hite, Stephen E. Russek, David P. Pappas
Electrical transport characteristics for epitaxially grown Ag/Fe/Ag multilayers on GaAs(100) and GaAs(110) have been studied under various growth conditions. The surfaces and structure of the multilayer were characterized by low energy electron diffraction

Microwave Properties of Low-Temperature Co-Fired Ceramic Systems

July 1, 2003
Author(s)
Richard G. Geyer, Liang Chai, Aziz Shaikh, Vern Stygar
Co-fired, patterned multi-layer ceramic structures can provide RF designers with the means for compact, dense microwave circuit and component design spanning the frequency range from 800 MHz to 77 GHz. Critical parameters affecting the performance of these

Magneto-optic effects in spin-injection devices

June 23, 2003
Author(s)
Steve Ruggiero, Anthony Williams, Carol Tanner, S. Potashnik, John M. Moreland, William Rippard
The magneto-optic properties of semi-transparent ferromagnetic films are presented in the context of ferromagnet/GaAs spin-injection devices. We have measured the polarization-dependent photoresponse and magneto-optic properties of Co/i}n-GaAs, Co/p-GaAs

An Optimal Multiline TRL Calibration Algorithm

June 17, 2003
Author(s)
Dylan Williams, Jack Wang, Uwe Arz
We examine the performance of two on-wafer multiline TRL calibration algorithms, the popular multiline TRL algorithm implemented in the MultiCal software package and a newly implemented iterative algorithm designed to give optimal results in the presence

Development of a Quantum Based Microwave Power Measurement

June 17, 2003
Author(s)
Thomas P. Crowley, E. A. Donley, T P. Heavner, John R. Juroshek, Billy F. Riddle
An initial proof-of-concept experiment to measure microwave power based on quantum-mechanical principles is presented. Rabi oscillations between two hyperfine levels of the cesium ground state are measured and used to determine the RF magnetic field

Extraction of Conversion Matrices for P-HEMTs based on Vectorial Large-Signal Measurements

June 17, 2003
Author(s)
Alessandro Cidronali, Kuldip Gupta, Jeffrey Jargon, Kate Remley, Donald C. DeGroot, Gianfranco Manes
This paper introduces a new technique which allows us to measure the admittance conversion matrix of a two-port device, using a large signal vector network analyzer. This method is applied to extract the conversion matrix of a 0.25 um PHEMT, driven by a 4

Multisine Excitation for ACPR Measurements

June 17, 2003
Author(s)
Catherine A. Remley
We use a simlator to compare ACPR measurements of a nonlinear device excited with various multisine signals to ACPR measurements of the same device excited with a QPSK-modulated pseudorandom digital signal. We examine four common types of multisine

Sampling Oscilloscope Models and Calibrations

June 17, 2003
Author(s)
Kate Remley, Dylan Williams
We discuss the basic principles of operation of electrical sampling oscilloscopes and describe circuit models developed to design, characterize, and help explain their operation. We survey common oscilloscope calibration schemes that correct for finite

Phase Detrending for Measured Multisine Signals

June 13, 2003
Author(s)
Kate Remley, Dylan Williams, Dominique Schreurs, Giovanni Loglio, Cidronali Alessandro
We develop a method to detrend the phases of measured multisine signals. We find a time reference that removes the linear component of the measured phases and aligns them to their expected values to the precision specified by the user. An initial guess is

Cyrogenic pulsed inductive microwave magnetometer

May 15, 2003
Author(s)
Anthony B. Kos, John P. Nibarger, Radek Lopusnik, Thomas J. Silva, Zbigniew J. Celinski
A cryogenic pulsed inductive microwave magnetometer is used to characterize the switching dynamics in thin-film materials at low temperatures and microwave frequencies. The system is contained inside a 20-cm-dia ultrahigh vacuum chamber and cooled by a

High-Frequency Measurements of Spin Valve Films and Devices

May 15, 2003
Author(s)
Shehzaad F. Kaka, John P. Nibarger, Stephen E. Russek, N. A. Stutzke, S. L. Burkett
High-frequency measurements of spin-valve films and devices, made using several different measurement techniques, are presented and compared. Pulsed inductive measurements were made on sheet films and provide insight into the intrinsic dynamical properties

Iron and Permalloy Based Magnetic Monolithic Tunable Microwave Devices

May 15, 2003
Author(s)
Bijoy Kuanr, Leszek Malkinski, Robert E. Camley, Zbigniew Celinski, Pavel Kabos
We constructed a series of Magnetic Monolithic tunable Microwave notch-filters and phase shifters in co-planer waveguide (CPW) geometry on GaAs substrates using Fe and Permalloy as magnetic materials. In contrast to previous work with Molecular Beam

Measuring the Invasiveness of High-Impedance Probes

May 14, 2003
Author(s)
Uwe Arz, Pavel Kabos, Dylan Williams
We use on-wafer measurements to characterize the invasiveness of high-impedance probes over a broad frequency range. We show that a two-port representation characterizing the invasiveness of the probe can also be determined from a calculation of the probe

Atomic vapor cells for miniature frequency references

May 8, 2003
Author(s)
Svenja A. Knappe, V. Velichansky, Hugh Robinson, Li-Anne Liew, John M. Moreland, John Kitching, Leo W. Hollberg
We report on the fabrication of millimeter-sized vapor cells and their performance on atomic clocks based on coherent population trapping (CPT). We discuss two fabrication techniques, the first one based on hollow-core pyrex fibers, fused with a CO 2 laser

Causal Characteristic Impedance of Planar Transmission Lines

May 1, 2003
Author(s)
Dylan F. Williams, Bradley K. Alpert, Uwe Arz, Hartmut Grabinski
Abstract: We compute power-voltage, power-current, and causal definitions of the characteristic impedance of microstrip and coplanar-waveguide transmission lines on insulating and conducting silicon substrates, and compare to measurement.

Introducing Material Dispersion in ADI-FDTD

May 1, 2003
Author(s)
Shawn W. Staker, Christopher L. Holloway, Melinda Piket-May
This paper presents the incorporation of material dispersion into ADI-FDTD, ADI-FDTD is an uncontionally stable mathod, allowing the time step to be increased beyond the CFL bound. ADI class problems result in a reduced execution time, while maintaining
Displaying 726 - 750 of 1560