Foto del docente

Alberto Santarelli

Associate Professor

Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi"

Academic discipline: ING-INF/01 Electronic Engineering

Research

Keywords: Nonlinear behavioural models for microwave transistors and components Characterisation Techniques of circuits and transistors Nonlinear circuit design Power amplifiers MIC - Microwave Integrated Circuit CAD - Computer Aided Design Digital Predistortion

1. Nonlinear modelling of high-frequency transistors and components. Model implementation techniques into CAD tools for Hybrid and Microwave Integrated Circuits

2. Electro-thermal modelling of compound semiconductor electron devices (GaAs, GaN)

3. Experimental characterization and measurement techniques of electron devices and circuits for telecommunications

4. Power Amplifier design for radio-communications 



Nonlinear modelling of high-frequency transistors and model implementation techniques into CAD tools for Microwave Integrated Circuits

The development of empirical nonlinear transistor models is made particularly difficult by the simultaneous presence of nonlinearity and dynamics. This research activity deals with the definition of nonlinear models of microwave transistors, which take into account the complex dynamic behaviour observed at increasing fundamental frequencies of operation (including non-quasi-static effects). These models have to be easily identified on the basis of multi-bias measurements both under static and dynamic regime. They also should be numerically efficient, enabling faster circuit design procedures.

Electro-thermal modelling of compound semiconductor electron devices (GaAs, GaN)

Accurate electro-thermal models of high-frequency transistors (MESFETs, HFETs, PHEMTs), are typically needed in order to obtain reliable predictions of the behaviour of power amplifiers for telecommunication systems. In particular, dispersive phenomena due to thermal effects and charge trappings taking place in Field Effect Transistors have to be taken into account. These dispersive phenomena cause important deviations of dynamic drain current characteristics with respect to static measurements. Since these deviations are dramatically bias-dependent, the definition of a definitive solution to the modelling has not yet been given by researchers.

Experimental characterization and measurement techniques of electron devices and circuits for telecommunications

Experimental characterization of electron devices and circuits represents a fundamental step both for extracting electrical component models and for verifying their operating features. This research activity deals with the development of experimental measurement setups for the characterization of thermal dynamics and other phenomena showing a similarly “slow” dynamics, due to charge trappings at the inter-layer interfaces of field effect transistors. To this aim, both sinusoidal and pulsed excitations are taken into account as possible valuable solutions. The research activity also deals with the definition of thermal resistance/impedance identification procedures.

Power Amplifier design for radio-communications

This research activity is aimed at the development of design methodologies for power amplifiers to be used for radio-communications. Important trade-off are taken into account between the need for high energetic efficiency and low-distortion constraints. On the basis of accurate nonlinear device models, near optimal source and load terminations are sought for with the goal of achieving maximum output power with assigned constraints in terms of inter-modulation distortion, power gain and parametric sensitivity. In this framework, the numerical efficiency of the design procedure implemented into the CAD program also plays an important role.