< Back to previous page
Project
Combined Low- and High-Frequency Nonlinear Characterization and Modeling
Accurate characterization and modeling of transistors are essential forthe successful design of electronic
circuits. In many microwave circuit applications, transistors experience high-frequency
electrical signals with large excursions. These signals drive the devices into
a nonlinear regime of operation. With the introduction of new materials in the
transistor fabrication process, additional effects, such as low-frequency
dispersion, must be taken into account for a more complete investigation of
transistor characteristics.
This work has aimed in the first place at characterizing transistors through nonlinear vector measurements. A time-domain based high-frequency large-signal network analyzer (LSNA) has been
extended towards the low-frequency range. When modulated excitations are
applied, the low-frequency part operates synchronously with the core RF LSNA. Otherwise
it can work like a stand-alone low-frequency LSNA. With this instrument, low-frequency
dispersive effects under large-signal operation can be captured more accurately
than before.
Next, the calibrated large-signal voltage and current waveforms acquired by the combined low- and
high-frequency LSNAs have been exploited to generate nonlinear transistor
models. Furthermore a waveform based nonlinear de-embedding procedure has been
developed. This technique can be adapted for improving waveform engineering
techniques aimed at the design of high-frequency power amplifiers. Both the
modeling and the de-embedding procedure are independent of the investigated
transistor technology and therefore can be - in principle - adopted for any
type of active device.
circuits. In many microwave circuit applications, transistors experience high-frequency
electrical signals with large excursions. These signals drive the devices into
a nonlinear regime of operation. With the introduction of new materials in the
transistor fabrication process, additional effects, such as low-frequency
dispersion, must be taken into account for a more complete investigation of
transistor characteristics.
This work has aimed in the first place at characterizing transistors through nonlinear vector measurements. A time-domain based high-frequency large-signal network analyzer (LSNA) has been
extended towards the low-frequency range. When modulated excitations are
applied, the low-frequency part operates synchronously with the core RF LSNA. Otherwise
it can work like a stand-alone low-frequency LSNA. With this instrument, low-frequency
dispersive effects under large-signal operation can be captured more accurately
than before.
Next, the calibrated large-signal voltage and current waveforms acquired by the combined low- and
high-frequency LSNAs have been exploited to generate nonlinear transistor
models. Furthermore a waveform based nonlinear de-embedding procedure has been
developed. This technique can be adapted for improving waveform engineering
techniques aimed at the design of high-frequency power amplifiers. Both the
modeling and the de-embedding procedure are independent of the investigated
transistor technology and therefore can be - in principle - adopted for any
type of active device.
Date:1 Jan 2008 → 16 May 2012
Keywords:low-frequency dispersion, microwave transistors, microwave circuits, behavioural modelling
Disciplines:Nanotechnology, Design theories and methods, Communications, Communications technology
Project type:PhD project