Wide Band MOS Techniques.

Analog MOS circuits that amplify and detect signals at high frequencies are now being designed and manufactured. This is possible because of the speed of fine line MOS transistors. Modern CMOS process technologies with gate lengths on the order of 1micron produce transistors with f sub T's approaching 5 Ghz. In this tutorial, the use of f sub T as a figure of merit for MOS transistors is explained and examples of wide band amplifier circuits are shown. A simple theory for f sub T scaling is discussed and compared to measured results obtained from 3 scaled CMOS technologies. A discrepancy between predicted and measured f sub T results is observed due to thin gate dielectrics and short channel fringing field effects in these fine line MOS devices.