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By means of enhanced Monte Carlo numerical simulations parallelized on GPUs we study the critical properties of the spin-glass-like model for the mode-locked glassy random laser, a $4$-spin model with complex spins with a global spherical constraint and quenched random interactions. Implementing two different boundary conditions for the mode frequencies we identify the critical points and the critical indices of the random lasing phase transition with finite size scaling techniques. The outcome of the scaling analysis is that the mode-locked random laser universality class is compatible with a mean-field one, though different from the mean-field class of the Random Energy Model and of the glassy random laser in the narrow band approximation, that is, the fully connected version of the present model. The low temperature (high pumping) phase is finally characterized by means of the overlap distribution and evidence for the onset of replica symmetry breaking in the lasing regime is provided.

The design and the characterization of a non-linear target to test an intermodulation radar was performed using the AWR design environment Version 22 by Cadence software. Two experimental setups for intermodulation measurements were realized in order to characterize connectorized or antenna-equipped devices. Both setups were modeled using the VSS software available inside AWR Version 22. The comparison between measurements and simulations on the designed target showed a very good agreement. Intermodulation measurements were performed on connectorized devices present inside electronic systems and on various transceiver available on the market. This experimental study evidenced that the non-linearities of devices such as amplifiers and mixers are visible at their access ports even when the device is switched off. Moreover, this study highlights the ability of an intermodulation radar to remotely detect the presence of a particular transceiver, even when the latter is switched off, thanks to the specific frequency response of its intermodulation products. [ABSTRACT FROM AUTHOR]

A new method is described that has combined frequency-domain Fourier series expansion and space-domain polynomial expansion of the physical quantities inside the semi-conductor for an efficient numerical modeling of high-frequency active devices. An algorithm is described for a faster solution of the transport equations together with Poisson's equation and its results are in accordance with standard finite-differences formulations.

In this study, a two-stage simulation method is presented for the efficient design of frequency dividers using harmonic balance. The first stage uses a modified conversion matrix approach to select the subharmonic loads of the active element enabling the frequency division by a given order N. The second stage makes use of an auxiliary generator to obtain and modify the sub-harmonic-power curve versus the input power or input frequency. Systematic simulation tools are used to eliminate common hysteresis phenomena, which require additional constraints to minimize the disturbance of the original frequency-division bands and output power. A harmonic-balance technique to distinguish between subcritical flip bifurcations, associated with hystereses, and supercritical ones is presented, to our knowledge, for the first time. A technique is also derived to transform subcritical bifurcations into supercritical ones. The techniques have been successfully applied to a frequency divider by 2 at 630 MHz. Index Terms--Bifurcation, conversion matrix, frequency divider, stability.

A global physical/electromagnetic high electronmobility transistor (HEMT) simulation approach, entirely in the frequency domain, is here described for microwave computeraided design applications. The frequency-domain spectral balance technique for the solution of steady-state nonlinear differential equations is applied to the moments of Boltzmann's transport equation for the analysis of the intrinsic active part of the device, yielding a very simple formulation. A numerical electromagnetic solver in the frequency domain is used for the analysis of the extrinsic passive embedding and access structure. The two analyzes are coupled, and give a self-consistent global description of the device. The frequency-domain formulation allows easy inclusion of frequency-dependent parameters of the semiconductor, and a natural extension to multitone analysis, without the need for cumbersome time-frequency transformations. The technique is applied to a quasi-2-D hydrodynamic modeling of the active device for simplicity, but is suitable for more comprehensive approaches as well. DC and small-signal microwave results up to 40 GHz are obtained for a 0.3-[micro]m gate-length AIGaAs-InGaAs-GaAs pseudomorphic HEMT transistor, and compared to experimental data. Index Terms--Electron device modeling, frequency-domain analysis, global modeling, monolithic microwave integrated circuit, physic-based analysis.

An effective technique, which is based only on geometrical and physical data, is presented for the analysis of high-frequency FETs. The intrinsic part of this electron device is described by a quasi-two-dimensional hydrodynamic transport model, coupled to a numerical electromagnetic field time domain solver in three dimensions that analyzes the passive part of the FET. Such an analysis is entirely performed in the time domain, thus allowing linear and nonlinear operations. The obtained data give insights to some parameters affecting the signal distribution through the entire device structure; a comprehensive discussion of these is given for a test device. In order to prove the validity of the approach, the bias-dependent small-signal analysis is compared with the corresponding measurements up to 50 GHz for two 0.3-[micro]m gate-length AlGaAs-InGaAs-GaAs pseudomorphic high electron-mobility transistors, each having two gate fingers of 25-[micro]m and 100-[micro]m width, at bias points ranging from Idss to the pinchoff regime. The accuracy and the efficiency of the approach make it suitable for device optimization. Index Terms--Electron device modeling, global modeling, microwave monolithic integrated circuit, pseudomorphic high electron-mobility transistors (pHEMT).

A nonlinear mixed analysis/optimization algorithm for the design of microwave power amplifiers is presented. Matching conditions for optimum power and efficiency performance are imposed together with the balancing equations of the nonlinear analysis in a consistent way. The analysis/preoptimization of the power stage requires a computation time comparable to or smaller than a single conventional harmonic balance analysis. The algorithm forms the basis of a design procedure for the fulfilment of design specifications in terms of output power, power-added efficiency, and gain. Comparisons to the results of commercial CAD nonlinear analysis programs are presented.

RF and Microwave active filters design by the use of grounded active inductor (AI) is here presented. The proposed single transistor AI emulates an inductor behaviour by implementing a passive variable phase and amplitude compensating network and amplifiers, forming a similar gyrator-C architecture allowing its use in LC filters architectures at high frequencies with high quality factor and reduced occupied chip area. The design method can be applied with success, in particular, for the design of bandpass filters with very high performances in terms integration and application from RF to Microwave frequency range achieving active filters with relatively high dynamic range, constant Q and also easy frequency tuning capability. [ABSTRACT FROM AUTHOR]