1,721,000 research outputs found
TCAD-based Pseudo-Common-Gate X-PAR Model for GaAs Stacked Power Amplifier Design
Full text linkSeries device stacking has proved to be a very interesting solution for developing high-voltage high-power microwave amplifiers in low-breakdown technologies. The availability of 3-terminal device nonlinear models that are accurate and reliable, yet computationally efficient, in simulating a pseudo-common-gate stage are of crucial importance for developing a stacked power amplifier. This work presents the extraction and validation of a 3-terminal X-parameter model of a GaAs MESFET from physics-based simulations. Remarkable accuracy can be obtained by properly selecting the port terminations, accounting for the peculiar circuit scheme adopted for model extraction
La Fondazione Cassa di risparmio della provincia di Teramo
No full textIl capitolo è parte di un volume che raccoglie i risultati di una ricerca e di un percorso di sperimentazione a livello nazionale sulle fondazioni di origine bancaria. Tali attività si ponevano un duplice obiettivo: da un lato, analizzare in profondità gli interventi di un certo numero di organizzazioni rappresentative dell’universo delle fondazioni piccole e medio-grandi; dall’altro, sperimentare un modello, messo a punto con le organizzazioni partecipanti, che prevedeva una serie di operazioni e procedure per innalzare l’impatto del loro intervento nella realtà locale. Il capitolo si focalizza sulla Fondazione Cassa di Risparmio della Provincia di Teramo. La ricerca è stata condotta seguendo un approccio mixed-method, utilizzando più metodi e tecniche di rilevazione (raccolta e analisi di documenti, raccolta e analisi di dati quantitativi, interviste semi-strutturate a membri della fondazione, interviste semi-strutturate a osservatori privilegiati). È emerso che, nonostante un contesto di condizioni non sempre favorevole, soprattutto dopo la crisi finanziaria, la fondazione svolge un ruolo importante nella produzione di beni collettivi per il territorio di riferimento, agevolata da una gestione selettiva e focalizzata delle risorse, all’interno però di una strategia di sviluppo che promuove la cooperazione tra vari attori locali. E il percorso di sperimentazione ha enfatizzato alcune possibilità di rafforzamento di tale ruolo
Global Assessment of PA variability through concurrent Physics-based X-parameter and Electro-Magnetic simulations
Full text linkThe novel technique introduced in [1] is exploited to address a full variability analysis of a GaAs MMIC X-band power amplifier, including the statistical variations of several technological parameters, both in the active and passive components. The active device is modelled by means of X-parameters, directly extracted from physics-based analysis. A non-50 O X-Par model is used to take into account the input port mismatch with respect to the conventional 50 O reference. The scattering parameters of the passive structures are extracted from accurate electromagnetic simulations and then imported into the circuit simulator through data intercharge files (e.g. MDIF or CITIfile) as a function of the most important MMIC fabrication parameters, e.g. the thickness of the MIM capacitor dielectric layer. The analysis shows that more than 10% of output power variations can be ascribed to the concurrent MIM and doping variations in conventional GaAs MMIC technology
A Simple Method to Identify Parametric Oscillations in Power Amplifiers Using Harmonic Balance Solvers
Full text linkA qualitative method to verify the presence of parametric oscillations at f_0/2 in power amplifiers (PAs) is presented and validated. It relies on the simultaneous application of fundamental and subharmonic tones to trigger possible parametric oscillations and can be implemented in any commercial harmonic balance solver without requiring any external software that may be expensive or however not available to the designer. Wide applicability is guaranteed by the fact that this method does not require access to any internal node of the circuit. In fact, the amplifier is handled as a black-box where only the input and output ports are accessible. The stability check is first demonstrated on a simplified case study and then validated on a real K-band integrated PA, where it correctly reproduces with simulations the parametric oscillations observed by measurements. On the redesigned amplifier, the proposed test predicted the absence of oscillations, which has been confirmed by the experimental characterization
Compact GaN-based Stacked Cells for 5G Applications at 26 GHz
Full text linkThis work presents the development of two 2-FET stacked cells at 26 GHz in the WIN Semiconductors 150 nm power GaN/SiC technology. Two different compact layouts, based on the same circuit scheme, are designed targeting similar performance in the FR2 5G frequency band. One version favoring distance between components, to relieve electromagnetic cross-talk, and the other favoring instead symmetry. The cells have been conceived as basic building blocks for the development of high-power 5G amplifiers, rather than as stand-alone amplifiers, hence including only input matching and stabilization networks. Based on large-signal simulations on the optimum load, the cells are expected to deliver around 34 dBm with an efficiency higher than 35% at 26 GHz, and a linear gain of 10 dB. The output power performance is maintained from 24.5 GHz to 27.5 GHz, where the saturated efficiency is above 30 % for both cells. The small-signal experimental characterization results are in very good agreement with the simulations, proving the effectiveness of the electromagnetic simulation setup adopted for all the passive structures, despite the challenges posed by the compact layouts
Optimisation of a Doherty power amplifier based on dual-input characterisation
Full text linkThe success of the Doherty architecture compared to other efficiency enhancement techniques derives mainly from its simple design and full-RF nature, not requiring complex digital signal processing to achieve high back-off efficiency. In this work we propose a design strategy for the optimisation of a Doherty power amplifier to mitigate the typical practical issues of this architecture related to inaccuracy of the non-linear model and of the manufacturing. The approach is based on the experimental characterisation of a dual-input Doherty prototype without input section. This test structure is obtained from a single-input Doherty amplifier, designed only through non-linear simulations, by removing the input section and allowing for separate control of the two RF inputs. From the collected data, approximated functions for the phase shift and power splitting versus frequency are identified to be realizable in hardware with RF networks. Compared to the reference single-input Doherty stage, a significantly improved behavior is registered in terms of output power (up to 2.7 dB), efficiency at saturation and back-off (30 % and 15 % respectively) and power gain (2 dB)
Efficient sensitivity and variability analysis of nonlinear microwave stages through concurrent TCAD and EM modeling
Full text linkAn accurate, yet computationally efficient, Computer Aided Design (CAD) framework is proposed for the concurrent variability analysis of the active and a passive part of an RF/microwave nonlinear stage. Both the active and passive part are modeled, fully retaining a link to their physical and technological parameters. This allows for a global assessment of the nonlinear stage sensitivity and variability due to process variations. The active device is first modeled through Technology CAD (TCAD); then, the model is implemented within an RF/microwave Electronic Design Automation (EDA) circuit simulator through X-parameters. The passive part is modeled by means of accurate electromagnetic (EM) simulations and then taken into account in the circuit simulator through parametrized S-parameters. The method is demonstrated by analyzing a deep class AB Power Amplifier (PA) at 12 GHz in GaAs FET technology. In particular, a Monte Carlo analysis of the output power variability around the nominal value of 26.4 dBm due to technological variations of both active device and output matching network is presented. The active device variability is shown to dominate over the passive structure one, even if up to 30% of the overall variance is due to the passive elements at intermediate input power levels
Thermal modeling of RF FinFET PAs through temperature-dependent X-parameters extracted from physics-based simulations
Full text linkFinFET RF technology is increasingly investigated for the deployment of 5G communication systems and beyond. Thermal management represents one of the main problems that must be addressed for the successful design of FinFET-based microwave power amplifiers. In fact, the peculiar 3D device structure inhibits the efficient heat dissipation through the substrate, requiring an accurate temperature-dependent nonlinear device model. In this paper we extract the FinFET X-parameters from accurate temperature dependent physics-based simulations. The T -dependent X-parameters are then included into Keysight ADS using a dedicated isolated port to represent the device junction temperature. With this modeling approach, we present the T -dependent analysis of a low-power FinFET amplifier at 70 GHz, showing that with T increasing from 300 K to 390 K we have more than 15% P sat loss, 2 dB gain degradation and 10 percentage points efficiency loss
Variability-aware MMIC design through multiphysics modelling
Full text linkWe present a novel multiphysics approach to the variability-aware modelling of MMIC stages, including technological variations in both the active devices and in the passive structures used to implement the matching networks. The models are based on accurate physical simulations via the TCAD numerical analysis of the active device, and electro-magnetic simulations of the passives. Black-box models are then extracted and implemented into circuit simulators, using parameter-dependent X-parameters and scattering matrix. In both cases, the link with the underlying technology is always retained. After model validation, we present the statistical analysis of an X-band GaAs power amplifier. We show that the stage is highly affected by process induced variability, with spreads up to 3 dB of output power, 1.5 dB of operative gain, and more than 10 percentage points of drain efficiency
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