3,128 research outputs found
Intermodulation distortion in a directly modulated semiconductor injection laser
A most important quantity in high-frequency analog transmission is the intermodulation distortion product. Experimental studies of the third order intermodulation distortion products in the modulation response of high-speed semiconductor lasers give very low values (< â60 dB) at low frequencies, an increase at a rate of 40 dB/dec as the modulation frequency is increased, and a leveling off at one-half of the relaxation oscillation resonance frequency. These experimental results can be well explained by a theory based on a perturbative analysis of laser dynamics
Intermodulation distortion from receiver non-linear phase characteristics Final report
Computation of intermodulation distortion levels produced by telemetry system predetection filte
The study of multipactor breakdown in space electronic systems fourth status report, jan. 1965
Harmonic and noise current measurements, and intermodulation distortion coefficients for studying multipactor radio frequency discharge in space electronic system
Intermodulation distortion in high dynamic range microwave fiber-optic links with linearized modulators
Linearization of integrated optic intensity modulators significantly reduces the two-tone intermodulation distortion. The resulting intermodulation distortion produced by these modulators then varies as the input power to the fifth-order link system, the overall intermodulation product is a combination of third-order and higher-order terms. The authors determine the dynamic range of a cascaded microwave network consisting of a preamplifier, a high-dynamic-range fiber-optic link with a highly linear modulator, and a postamplifier. An expression is found that relates the intermodulation power at the output to the relative suppression from the signal level. As an example, a hypothetical 10-GHz low-distortion fiber-optic link that has a dynamic range of 125 dB in a bandwidth of 1 Hz is cascaded with various preamplifiers, and it is shown that the dynamic range of the system is reduced by as much as 20 dB, depending on the third-order intercept of the amplifier
Nonlinear mechanisms in passive microwave devices
Premi extraordinari doctorat curs 2010-2011, Ă mbit dâEnginyeria de les TICThe telecommunications industry follows a tendency towards smaller devices, higher power and higher frequency, which imply an increase on the complexity of the electronics involved. Moreover, there is a need for extended capabilities like frequency tunable devices, ultra-low losses or high power handling, which make use of advanced materials for these purposes. In addition, increasingly demanding communication standards and regulations push the limits of the acceptable performance degrading indicators. This is the case of nonlinearities, whose effects, like increased Adjacent Channel Power Ratio (ACPR), harmonics, or intermodulation distortion among others, are being included in the performance requirements, as maximum tolerable levels.
In this context, proper modeling of the devices at the design stage is of crucial importance in predicting not only the device performance but also the global system indicators and to make sure that the requirements are fulfilled. In accordance with that, this work proposes the necessary steps for circuit models implementation of different passive microwave devices, from the linear and nonlinear measurements to the simulations to validate them. Bulk acoustic wave resonators and transmission lines made of high temperature superconductors, ferroelectrics or regular metals and dielectrics are the subject of this work. Both phenomenological and physical approaches are considered and circuit models are proposed and compared with measurements. The nonlinear observables, being harmonics, intermodulation distortion, and saturation or detuning, are properly related to the material properties that originate them. The obtained models can be used in circuit simulators to predict the performance of these microwave devices under complex modulated signals, or even be used to predict their performance when integrated into more complex systems. A key step to achieve this goal is an accurate characterization of materials and devices, which is faced by making use of advanced measurement techniques. Therefore, considerations on special measurement setups are being made along this thesis.Award-winningPostprint (published version
Microwave intermodulation distortion of MgB2 thin films
The two tone intermodulation arising in MgB2 thin films deposited in-situ by
planar magnetron sputtering on sapphire substrates is studied. Samples are
characterised using an open-ended dielectric puck resonator operating at 8.8
GHz. The experimental results show that the third order products increase with
the two-tone input power with a slope ranging between 1.5 and 2.3. The
behaviour can be understood introducing a mechanism of vortex penetration in
grain boundaries as the most plausible source of non linearities in these
films. This assumption is confirmed by the analysis of the field dependence of
the surface resistance, that show a linear behaviour at all temperatures under
test.Comment: 13 pages, 3 figures; to be published in Appl. Phys. Let
Probing the Locally Generated Even and Odd Order Nonlinearity in Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O (2212) Microwave Resonators around TC
Spatial scanning of the synchronously generated 2nd and 3rd order
intermodulation distortion in superconducting resonators uncovers local
nonlinearity hot spots, and possible time reversal symmetry breaking, using a
simple probe fashioned from coaxial cable. It is clear that even and odd order
nonlinearity in these samples do not share the same physical origins, as their
temperature and static magnetic field dependences are quite different. 2nd
order intermodulation distortion (IMD) remains strong in these measurements as
the temperature continues to drop below TC to 77K even though the 3rd order
peaks near TC and becomes smaller at lower temperature as predicted by the
nonlinear Meissner effect. Both YBa2Cu3O7 and Tl2Ba2CaCu2O8 resonators of the
same structure exhibit similar temperature dependence in the 2nd order with 2nd
order remaining high at lower temperature. The YBa2Cu3O7 sample has lower 3rd
order IMD with a pronounced peak at TC
Nonlinear Performance of BAW Filters Including BST Capacitors
This paper evaluates the nonlinear effects occurring in a bulk acoustic wave (BAW) filter which includes barium strontium titanate (BST) capacitors to cancel the electrostatic capacitance of the BAW resonators. To do that we consider the nonlinear effects on the BAW resonators by use of a nonlinear Mason model. This model accounts for the distributed nonlinearities inherent in the materials forming the resonator. The whole filter is then implemented by properly connecting the resonators in a balanced configuration. Additional BST capacitors are included in the filter topology. The nonlinear behavior of the BST capacitors is also accounted in the overall nonlinear assessment. The whole circuit is then used to evaluate its nonlinear behavior. It is found that the nonlinear contribution arising from the ferroelectric nature of the BST capacitors makes it impractical to fulfill the linearity requirements of commercial filters
Investigation into intermodulation distortion in HEMTs using a quasi-2-D physical model
The need for both linear and efficient pseudomorphic high electron-mobility transistors (pHEMTs) for modern wireless handsets necessitates a thorough understanding of the origins of intermodulation distortion at the device level. For the first time, the dynamic large-signal internal physical behavior of a pHEMT is examined using a quasi-two-dimensional physical device model.
The model accounts fully for device-circuit interaction and is validated experimentally for a two-tone experiment around 5 GHz
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