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Variable domain transformation for linear PAC analysis of mixed-signal systems
This paper describes a method to perform linear AC analysis on mixed-signal systems which appear strongly nonlinear in the voltage domain but are linear in other variable domains. Common circuits like phase/delay-locked loops and duty-cycle correctors fall into this category, since they are designed to be linear with respect to phases, delays, and duty-cycles of the input and output clocks, respectively. The method uses variable domain translators to change the variables to which the AC perturbation is applied and from which the AC response is measured. By utilizing the efficient periodic AC (PAC) analysis available in commercial RF simulators, the circuit’s linear transfer function in the desired variable domain can be characterized without relying on extensive transient simulations. Furthermore, the variable domain translators enable the circuits to be macromodeled as weakly-nonlinear systems in the chosen domain and then converted to voltage-domain models, instead of being modeled as strongly-nonlinear systems directly
On the Perturbation of Self-Organized Urban Street Networks
We investigate urban street networks as a whole within the frameworks of
information physics and statistical physics. Urban street networks are
envisaged as evolving social systems subject to a Boltzmann-mesoscopic entropy
conservation. For self-organized urban street networks, our paradigm has
already allowed us to recover the effectively observed scale-free distribution
of roads and to foresee the distribution of junctions. The entropy conservation
is interpreted as the conservation of the surprisal of the city-dwellers for
their urban street network. In view to extend our investigations to other urban
street networks, we consider to perturb our model for self-organized urban
street networks by adding an external surprisal drift. We obtain the statistics
for slightly drifted self-organized urban street networks. Besides being
practical and manageable, this statistics separates the macroscopic evolution
scale parameter from the mesoscopic social parameters. This opens the door to
observational investigations on the universality of the evolution scale
parameter. Ultimately, we argue that the strength of the external surprisal
drift might be an indicator for the disengagement of the city-dwellers for
their city.Comment: 22 pages, 4 figures + 1 table, LaTeX2e+BMCArt+AmSLaTeX+enote
An approach to harmonic load- and source-pull measurements for high-efficiency PA design
High-efficiency power-amplifier design requires numerous efforts to investigate both input and output harmonic terminations effects. A simplified theoretical approach to clarify the relevance of such terminations is presented here, and design criteria to improve efficiency for high-frequency applications are briefly discussed. An advanced active load/source-pull test-bench has been used to validate theoretical harmonic tuning techniques, characterizing an active device. The adopted optimization strategy is presented, together with measured results obtained with a medium-power 1-mm MESFET at 1 GHz. Input second harmonic impedances effects are stressed, showing a drain efficiency spread between 37%-49% for a fixed input power level, corresponding to 1-dB compression. Finally, as predicted by the presented theory, after input second harmonic tuning, further improvements are obtained, increasing fundamental output load resistive part, demonstrating an additional drain efficiency enhancement, which reaches a level of 55% at 1-dB compression
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