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.
