Transformer coupled stacked FET power amplifiers

The development of high-power linear ultrahigh-frequency amplifiers is made difficult by the low impedance of the devices used in the output stage, wh ich causes matching difficulties and high radio-frequency current levels. A stacked field-effect transistor (FET) configuration is shown to reduce the se problems with its increased output impedance and lower current required for a given output power. A linear analysis of the stacked FET configuratio n is given, Two Class A monolithic microwave integrated circuit amplifiers are developed and subjected to one- and two-tone tests to demonstrate the p erformance of the stacked FET as a power amplifier at 900 MHz.