Large-signal modeling of SOI MESFETs

It has been demonstrated that sub-micron metal–semiconductor field-effect transistors (MESFETs) can be fabricated using a commercial 3.5 V silicon-on-insulator (SOI) CMOS foundry with no changes to the CMOS process flow. The SOI MESFETs demonstrate excellent RF capabilities and can operate at voltages that are at least 3X higher than the MOSFET breakdown voltage. If the high voltage capability is to be exploited in radio frequency integrated circuits it is important to develop an accurate empirical model of the device. This paper presents the SPICE model development of the SOI MESFET. A measurement-based approach is used to customize a commercially available, large-signal TOM3 MESFET model. Using the TOM3 model, an SOI MESFET Colpitts oscillator operating at 1.5 GHz has been simulated with an output swing of 7 V to illustrate the high voltage RF applications of the device.