The stackFET: an improved implementation of the dual gate FET

Abstract

A method of directly coupling two GaAs FET devices in series is described. The resulting structure, called a stackFET, is essentially an optimum implementation of a dual-gate GaAs FET in which the gain of the two FETs is combined in a series biased, DC-coupled arrangement. The RF interconnection of the stackFET is such that each individual FET acts as if it is operating in RF common-source mode, rather than a common-source/common-gate cascode combination. This results in much higher gain and stability, and very well-behaved matching and automatic gain control characteristics. A stackFET-based balanced amplifier module giving 22.5 dB of gain over the 2-8-GHz band is discussed.<>